Electrophotographic light-sensitive material

ABSTRACT

An electrophotographic light-sensitive material which has improved electrostatic characteristics and image forming performance and is excellent particularly in reproducibility of highly accurate image using a liquid developer and image forming performance upon a scanning exposure system using a laser beam of a low power. 
     The electrophotographic light-sensitive material contains, as a binder resin, at least one resin (A) which has a weight average molecular weight of from 1×10 3  to 2×10 4  and contains not less than 30% by weight of a polymer component of the formula (I) and from 0.5 to 15% by weight of a specified polar group-containing polymer component and at least one resin (B) which is a starlike polymer having a weight average molecular weight of from 3×10 4  to 1×10 6  and comprising an organic molecule having bonded thereto at least three polymer chains each containing a polymer component containing a specified polar group and a polymer component of the formula (I). ##STR1## wherein a 1  and a 2  : hydrogen, halogen, a cyano group, a hydrocarbon group, --COOR 4  or --COOR 4  bonded via a hydrocarbon group (R 4  : hydrocarbon group), and R 3  : a hydrocarbon group.

TECHNICAL FIELD

The present invention relates to an electrophotographic light-sensitivematerial, and more particularly to an electrophotographiclight-sensitive material which is excellent in electrostaticcharacteristics and moisture resistance.

TECHNICAL BACKGROUND

An electrophotographic light-sensitive material may have variousstructures depending upon the characteristics required or anelectrophotographic process to be employed.

Typical electrophotographic light-sensitive materials widely employedcomprise a support having provided thereon at least one photoconductivelayer and, if necessary, an insulating layer on the surface thereof.

The electrophotographic light-sensitive material comprising a supportand at least one photoconductive layer formed thereon is used for theimage formation by an ordinary electrophotographic process includingelectrostatic charging, imagewise exposure, development, and, ifdesired, transfer.

Furthermore, a process using an electrophotographic light-sensitivematerial as an offset master plate precursor for direct plate making iswidely practiced. In particular, a direct electrophotographiclithographic plate has recently become important as a system forprinting in the order of from several hundreds to several thousandsprints having a high image quality.

Under these circumstances, binder resins which are used for forming thephotoconductive layer of an electrophotographic light-sensitive materialare required to be excellent in the film-forming properties bythemselves and the capability of dispersing photoconductive powdertherein. Also, the photoconductive layer formed using the binder resinis required to have satisfactory adhesion to a base material or support.Further, the photoconductive layer formed by using the binder resin isrequired to have various excellent electrostatic characteristics such ashigh charging capacity, small dark decay, large light decay, and lessfatigue due to prior light-exposure and also have an excellent imageforming properties, and the photoconductive layer stably maintains theseelectrostatic properties in spite of the fluctuation in humidity at thetime of image formation.

Further, extensive studies have been made for lithographic printingplate precursors using an electrophotographic light-sensitive material,and for such a purpose, binder resins for a photoconductive layer whichsatisfy both the electrostatic characteristics as an electrophotographiclight-sensitive material and printing properties as a printing plateprecursor are required.

It has been found that the chemical structure of binder resin used in aphotoconductive layer which contains at least an inorganicphotoconductive substance, a spectral sensitizing dye and a binder resinhas a great influence upon the electrostatic characteristics as well assmoothness of the photoconductive layer. Among the electrostaticcharacteristics, dark charge retention rate (D.R.R.) andphotosensitivity are particularly affected.

Techniques for improvements in smoothness and electrostaticcharacteristics of a photoconductive layer by using a resin having a lowmolecular weight and containing an acidic group in a polymer componentconstituting the polymer main chain or at one terminal of the polymermain chain are described, for example, in JP-A-63-217354 (the term"JP-A" as used herein means an "unexamined published Japanese PatentApplication"), JP-A-1-70761, JP-A-2-64547, JP-A-2-93540 andJP-A-3-181948.

Further, techniques for improving a mechanical strength of aphotoconductive layer by using the above described low molecular weightresin together with a medium to high molecular weight resin aredescribed, for example, in JP-A-64-564, JP-A-63-220149, JP-A-63-220148,JP-A-1-280761, JP-A-1-116643, JP-A-1-169455, JP-A-2-69758,JP-A-2-167551, JP-A-1-211766, JP-A-2-34859, JP-A-2-68561, JP-A-2-135455,JP-A-2-34860, JP-A-2-96766, JP-A-2-40660, JP-A-2-53064, JP-A-2-103056,JP-A-2-56558, JP-A-3-29954, JP-A-3-75753, JP-A-3-77954, JP-A-3-42665,JP-A-3-92861, JP-A-3-92862, JP-A-3-53257, JP-A-3-92863, JP-A-3-206464,and JP-A-3-225344.

PROBLEMS TO BE SOLVED BY THE INVENTION

However, it has been found that, even in a case of using these resins ora combination of these resins, it is yet insufficient to keep the stableperformance in the case of greatly fluctuating the ambient conditionsfrom high-temperature and high-humidity to low-temperature andlow-humidity. In particular, in a scanning exposure system using asemiconductor laser beam, the exposure time becomes longer and alsothere is a restriction on the exposure intensity as compared to aconventional overall simultaneous exposure system using a visible light,and hence a higher performance has been required for the electrostaticcharacteristics, in particular, the dark charge retentioncharacteristics and photosensitivity.

Further, when the scanning exposure system using a semiconductor laserbeam is applied to hitherto known light-sensitive materials forelectrophotographic lithographic printing plate precursors, variousproblems may occur in that the difference between E_(1/2) and E_(1/10)is particularly large and the contrast of the duplicated image isdecreased. Moreover, it is difficult to reduce the remaining potentialafter exposure, which results in severe fog formation in duplicatedimage, and when employed as offset masters, edge marks of originalspasted up appear on the prints, in addition to the insufficientelectrostatic characteristics described above.

Moreover, it has been desired to develop a technique which canfaithfully reproduce highly accurate images of continuous gradation aswell as images composed of lines and dots using a liquid developer.However, the above-described known techniques are still insufficient tofulfill such a requirement. Specifically, in the known technique, theimproved electrostatic characteristics which are achieved by means ofthe low molecular weight resin may be sometimes deteriorated by using ittogether with the medium to high molecular weight resin. In fact, it hasbeen found that an electrophotographic light-sensitive material having aphotoconductive layer wherein the above described known resins are usedin combination may cause a problem on reproducibility of the abovedescribed highly accurate image (particularly, an image of continuousgradation) or on image forming performance in case of using a scanningexposure system with a laser beam of low power.

The present invention has been made for solving the problems ofconventional electrophotographic light-sensitive materials as describedabove.

An object of the present invention is to provide an electrophotographiclight-sensitive material having stable and excellent electrostaticcharacteristics and giving clear good images even when the ambientconditions during the formation of duplicated images are fluctuated tolow-temperature and low-humidity or to high-temperature andhigh-humidity.

Another object of the present invention is to provide a CPCelectrophotographic light-sensitive material having excellentelectrostatic characteristics and showing less environmental dependency.

A further object of the present invention is to provide anelectrophotographic light-sensitive material effective for a scanningexposure system using a semiconductor laser beam.

A still further object of the present invention is to provide anelectrophotographic lithographic printing plate precursor havingexcellent electrostatic characteristics (in particular, dark chargeretention characteristics and photosensitivity), capable of reproducinga faithfully duplicated image to the original (in particular, a highlyaccurate image of continuous gradation), forming neither overallbackground stains nor dotted background stains of prints, and showingexcellent printing durability.

Other objects of the present invention will become apparent from thefollowing description.

DISCLOSURE OF THE INVENTION

It has been found that the above described objects of the presentinvention are accomplished by an electrophotographic light-sensitivematerial having a photoconductive layer containing at least an inorganicphotoconductive substance, a spectral sensitizing dye and a binderresin, wherein the binder resin comprises at least one resin (A) shownbelow and at least one resin (B) shown below.

Resin (A):

A resin having a weight average molecular weight of from 1×10³ to 2×10⁴and containing not less than 30% by weight of a polymer componentcorresponding to a repeating unit represented by the general formula (I)described below and from 0.5 to 15% by weight of a polymer componentcontaining at least one polar group selected from --PO₃ H₂, --SO₃ H,--COOH, ##STR2## (wherein R¹ represents a hydrocarbon group or --OR²(wherein R² represents a hydrocarbon group)) and a cyclic acidanhydride-containing group. ##STR3## (wherein a¹ and a² each representsa hydrogen atom, a halogen atom, a cyano group, a hydrocarbon group,--COOR⁴ or --COOR⁴ bonded via a hydrocarbon group (wherein R⁴ representsa hydrocarbon group); and R³ represents a hydrocarbon group).

Resin (B):

A starlike polymer having a weight average molecular weight of from3×10⁴ to 1×10⁶ and comprising an organic molecule having bonded theretoat least three polymer chains each containing a polymer componentcontaining at least one polar group selected from the specified polargroups as described in the resin (A) above and a polymer componentcorresponding to a repeating unit represented by the general formula (I)as described in the resin (A) above, wherein the polymer contains thepolymer component containing a polar group in an amount of from 0.01 to10% by weight and the polymer component corresponding to the generalformula (I) in an amount not less than 30% by weight.

In short, the binder resin which can be used in the present inventioncomprises at least a low molecular weight polymer containing a polymercomponent represented by the general formula (I) described above and apolymer component containing the specified polar group described above(resin (A)) and a starlike polymer comprising an organic molecule havingbonded thereto at least three polymer chains each containing thespecified polar group-containing polymer component described above andthe polymer component corresponding to the general formula (I) describedabove (resin (B)).

As a result of various investigations, it has been found that in theknown technique wherein the low molecular weight resin containing apolar group is used together with the medium to high molecular weightresin, the improved electrostatic characteristics achieved by the lowmolecular weight resin are sometimes deteriorated by the medium to highmolecular weight resin used together as described above. Further, it hasbecome apparent that an appropriate action of medium to high molecularweight resin on the interaction between the photoconductive substance,spectral sensitizing dye and low molecular weight resin in thephotoconductive layer is an unexpectedly important factor.

It has been found that the above described objects can be effectivelyachieved by using the starlike polymer comprising an organic moleculehaving bonded thereto at least three polymer chains each containing thepolar group-containing component and the component corresponding to thegeneral formula (I) according to the present invention as a medium tohigh molecular weight resin to be used together with the low molecularweight resin (A) containing the polar group.

It is presumed that the electrostatic characteristics are stablymaintained at a high level as a result of synergistic effect of theresin (A) and resin (B) according to the present invention whereinparticles of inorganic photoconductive substance are sufficientlydispersed without the occurrence of aggregation, a spectral sensitizingdye and a chemical sensitizer are sufficiently adsorbed on the surfaceof particles of inorganic photoconductive substance, and the binderresin is sufficiently adsorbed to excessive active sites on the surfaceof the inorganic photoconductive substance to compensate the traps.

More specifically, the low molecular weight resin (A) containing thespecific polar group has the important function in that the resin issufficiently adsorbed on the surface of particles of the inorganicphotoconductive substance to disperse uniformly and to restrain theoccurrence of aggregation due to its short polymer chain and in thatadsorption of the spectral sensitizing dye on the inorganicphotoconductive substance is not disturbed.

Further, by using the medium to high molecular weight starlike polymercomprising an organic molecule having at least three polymer chains eachcontaining the specific components mechanical strength of thephotoconductive layer is remarkably increased. This is believed to bebased on that the polar group-containing component of the resin (B) hasa weak interaction with the particles of photoconductive substancecompared with the resin (A) and that the polymer chains of the resin (B)intertwine each other due to their starlike formation.

Moreover, according to the present invention the electrostaticcharacteristics are more improved in comparison with a case wherein aknown medium to high molecular weight resin is employed. This isbelieved to be based on that the resin (B) acts to control thedisturbance of adsorption of spectral sensitizing dye on the surface ofparticles of photoconductive substance due to the polar group present inthe polar group-containing portion which interacts with the particles ofphotoconductive substance.

As a result, it is presumed that the resin (B) appropriately effects oncontrolling the disturbance of adsorption of spectral sensitizing dye onthe surface of particles of photoconductive substance and theelectrophotographic interactions and increasing the strength of thephotoconductive layer in a system wherein the particles ofphotoconductive substance, spectral sensitizing dye and resin (A) arecoexistent with the resin (B), while details thereof are not clear.

This effect is especially remarkable in a case wherein polymethine dyesor phthalocyanine series pigments which are particularly effective asspectral sensitizing dyes for the region of near infrared to infraredlight are used.

When the electrophotographic light-sensitive material according to thepresent invention containing photoconductive zinc oxide as the inorganicphotoconductive substance is applied to a conventional direct printingplate precursor, extremely good water retentivity as well as theexcellent image forming performance can be obtained. More specifically,when the light-sensitive material according to the present invention issubjected to an electrophotographic process to form an duplicated image,oil-desensitization of non-image portions by chemical treatment with aconventional oil-desensitizing solution to prepare a printing plate, andprinting by an offset printing system, it exhibits excellentcharacteristics as a printing plate.

When the electrophotographic light-sensitive material according to thepresent invention is subjected to the oil-desensitizing treatment, thenon-image portions are rendered sufficiently hydrophilic to increasewater retentivity which results in remarkable increase in a number ofprints obtained. It is believed that these results are obtained by thefact that the condition is formed under which a chemical reaction forrendering the surface of zinc oxide hydrophilic upon theoil-desensitizing treatment is able to proceed easily and effectively.Specifically, zinc oxide particles are uniformly and sufficientlydispersed in the resin (A) and resin (B) used as a binder resin and thestate of binder resin present on or adjacent to the surface of zincoxide particles is proper to conduct an oil-desensitizing reaction withthe oil-desensitizing solution rapidly and effectively.

Now, the resin (A) which can be used as the binder resin for thephotoconductive layer of the electrophotographic light-sensitivematerial according to the present invention will be described in moredetail below.

The weight average molecular weight of the resin (A) is from 1×10³ to2×10⁴, and preferably from 3×10³ to 1×10⁴. The glass transition point ofthe resin (A) is preferably from -30° C. to 110° C., and more preferablyfrom -10° C. to 90° C.

If the weight average molecular weight of the resin (A) is less than1×10³, the film-forming property of the resin is lowered, thereby asufficient film strength cannot be maintained, while if the weightaverage molecular weight of the resin (A) is higher than 2×10⁴, theeffect of the present invention for obtaining stable duplicated imagesis reduced since fluctuations of dark decay retention rate andphotosensitivity of the photoconductive layer, in particular, thatcontaining a spectral sensitizing dye for sensitization in the range offrom near-infrared to infrared become somewhat large under severeconditions of high temperature and high humidity or low temperature andlow humidity.

The content of the polymer component corresponding to the repeating unitrepresented by the general formula (I) present in the resin (A) is notless than 30% by weight, preferably from 50 to 99% by weight, and thecontent of the polymer component containing the specific polar grouppresent in the resin (A) is from 0.5 to 15% by weight, preferably from 1to 10% by weight.

If the content of the polar group-containing component in the resin (A)is less than 0.5% by weight, the initial potential is low and thussatisfactory image density is hardly obtained. On the other hand, if thecontent of the polar group-containing component is larger than 15% byweight, various undesirable problems may occur, for example, thedispersibility is reduced, and further when the light-sensitive materialis used as an offset master plate, the occurrence of background stainsmay increase.

The repeating unit represented by the general formula (I) above which iscontained in the resin (A) in an amount of not less than 30% by weightwill be described in greater detail below.

In the general formula (I), a¹ and a² each preferably represents ahydrogen atom, a halogen atom (e.g., chlorine, and bromine), a cyanogroup, an alkyl group having from 1 to 4 carbon atoms (e.g., methyl,ethyl, propyl and butyl), --COOR⁴ or --COOR⁴ bonded via a hydrocarbongroup (wherein R⁴ represents an alkyl, alkenyl, aralkyl, alicyclic oraryl group which may be substituted, and specifically includes those asdescribed for R³ hereinafter). Preferably a¹ represents a hydrogen atomand a² represents a methyl group.

The hydrocarbon group in the above described --COOR⁴ group bonded via ahydrocarbon group includes, for example, a methylene group, an ethylenegroup, and a propylene group.

R³ preferably represents a hydrocarbon group having not more than 18carbon atoms, which may be substituted. The substituent for thehydrocarbon group may be any substituent other than the polar groupscontained in the polar group-containing polymer component describedabove. Suitable examples of the substituent include a halogen atom(e.g., fluorine, chlorine, and bromine), --OR⁵, --COOR⁵, and --OCOR⁵(wherein R⁵ represents an alkyl group having from 1 to 22 carbon atoms,e.g., methyl, ethyl, propyl, butyl, hexyl, octyl, decyl, dodecyl,hexadecyl, and octadecyl). Preferred examples of the hydrocarbon groupinclude an alkyl group having from 1 to 18 carbon atoms which may besubstituted (e.g., methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl,octyl, decyl, dodecyl, hexadecyl, octadecyl, 2-chloroethyl,2-bromoethyl, 2-cyanoethyl, 2-hydroxyethyl, 2-methoxycarbonylethyl,2-methoxyethyl, 2-ethoxyethyl, 3-hydroxypropyl and 3-bromopropyl), analkenyl group having from 2 to 18 carbon atoms which may be substituted(e.g., vinyl, allyl, 2-methyl-1-propenyl, 2-butenyl, 2-pentenyl,3-methyl-2-pentenyl, 1-pentenyl, 1-hexenyl, 2-hexenyl, and4-methyl-2-hexenyl), an aralkyl group having from 7 to 12 carbon atomswhich may be substituted (e.g., benzyl, phenethyl, 3-phenylpropyl,naphthylmethyl, 2-naphthylethyl, chlorobenzyl, bromobenzyl,methylbenzyl, ethylbenzyl, methoxybenzyl, dimethylbenzyl anddimethoxybenzyl), an alicyclic group having from 5 to 8 carbon atomswhich may be substituted (e.g., cyclopentyl, cyclohexyl,2-cyclohexylethyl, and 2-cyclopentylethyl), and an aromatic group havingfrom 6 to 12 carbon atoms which may be substituted (e.g., phenyl,naphthyl, tolyl, xylyl, propylphenyl, butylphenyl, octylphenyl,dodecylphenyl, methoxyphenyl, ethoxyphenyl, butoxyphenyl,decyloxyphenyl, chlorophenyl, dichlorophenyl, bromophenyl, cyanophenyl,acetylphenyl, methoxycarbonylphenyl, ethoxycarbonylphenyl,butoxycarbonylphenyl, acetamidophenyl, propioamidophenyl, anddodecyloylamidophenyl).

More preferably, the polymer component corresponding to the repeatingunit represented by the general formula (I) is a methacrylate componenthaving the specific aryl group represented by the general formula (Ia)and/or (Ib) described below. The low molecular weight resin containingthe specific aryl group-containing methacrylate polymer componentdescribed above is sometimes referred to as a resin (A') hereinafter.##STR4## wherein T₁ and T₂ each represents a hydrogen atom, a halogenatom, a hydrocarbon group having from 1 to 10 carbon atoms, --COR_(a) or--COOR_(a), wherein R_(a) represents a hydrocarbon group having from 1to 10 carbon atoms; and L₁ and L₂ each represents a mere bond or alinking group containing from 1 to 4 linking atoms, which connects--COO-- and the benzene ring.

In the resin (A'), the content of the methacrylate polymer componentcorresponding to the repeating unit represented by the general formula(Ia) and/or (Ib) is suitably not less than 30% by weight, preferablyfrom 50 to 97% by weight, and the content of polymer componentcontaining the specified polar group is suitably from 0.5 to 15% byweight, preferably from 1 to 10% by weight.

In case of using the resin (A'), the electrophotographiccharacteristics, particularly, V₁₀, D.R.R. and E_(1/10) of theelectrophotographic material can be furthermore improved.

In the general formula (Ia), T₁ and T₂ each preferably represents ahydrogen atom, a chlorine atom, a bromine atom, and, as a hydrocarbongroup having from 1 to 10 carbon atoms, an alkyl group having from 1 to4 carbon atoms (e.g., methyl, ethyl, propyl, and butyl), an aralkylgroup having from 7 to 9 carbon atoms (e.g., benzyl, phenethyl,3-phenylpropyl, chlorobenzyl, dichlorobenzyl, bromobenzyl, methylbenzyl,methoxybenzyl, and chloromethylbenzyl), an aryl group (e.g., phenyl,tolyl, xylyl, bromophenyl, methoxyphenyl, chlorophenyl, anddichlorophenyl), --COR_(a) or --COOR_(a) (wherein R_(a) preferablyrepresents any of the above-recited hydrocarbon groups described aspreferred hydrocarbon groups having from 1 to 10 carbon atoms).

In the general formulae (Ia) and (Ib), L₁ and L₂ each represents a merebond or a linking group containing from 1 to 4 linking atoms whichconnects between --COO-- and the benzene ring, e.g., .paren open-st.CH₂.paren close-st._(n).sbsb.1 (wherein n₁ represents an integer of from 1to 3), --CH₂ OCO--, --CH₂ CH₂ OCO--, .paren open-st.CH₂ O.parenclose-st._(m).sbsb.1 (wherein m₁ represents an integer of 1 or 2), and--CH₂ CH₂ O--, and preferably represents a mere bond or a linking groupcontaining from 1 to 2 linking atoms.

Specific examples of the polymer component corresponding to therepeating unit represented by the general formula (Ia) or (Ib) which canbe used in the resin (A) according to the present invention are setforth below, but the present invention should not be construed as beinglimited thereto. In the following formulae (a-1) to (a-17), n representsan integer of from 1 to 4; m represents an integer of from 0 to 3; prepresents an integer of from 1 to 3; R₁₀ to R₁₃ each represents --C_(n)H_(2n+1) or --(CH₂ .paren close-st._(m) C₆ H₅ (wherein n and m each hasthe same meaning as defined above); and X₁ and X₂, which may be the sameor different, each represents a hydrogen atom, --Cl, --Br or --I.##STR5##

Now, the polymer component having the specified polar group present inthe resin (A) will be described in detail below.

The polymer component having the specified polar group can exist eitherin the polymer chain of the resin (A), at one terminal of the polymerchain or both of them.

The polar group included in the polar group-containing polymer componentis selected from --PO₃ H₂, --SO₃ H, --COOH, ##STR6## and a cyclic acidanhydride-containing group, as described above.

In the group ##STR7## above, R¹ represents a hydrocarbon group or --OR²(wherein R² represents a hydrocarbon group). The hydrocarbon grouprepresented by R¹ or R² preferably includes an aliphatic group havingfrom 1 to 22 carbon atoms which may be substituted (e.g., methyl, ethyl,propyl, butyl, hexyl, octyl, decyl, dodecyl, octadecyl, 2-chloroethyl,2-methoxyethyl, 3-ethoxypropyl, allyl, crotonyl, butenyl, cyclohexyl,benzyl, phenethyl, 3-phenylpropyl, methylbenzyl, chlorobenzyl,fluorobenzyl, and methoxybenzyl) and an aryl group which may besubstituted (e.g., phenyl, tolyl, ethylphenyl, propylphenyl,chlorophenyl, fluorophenyl, bromophenyl, chloromethylphenyl,dichlorophenyl, methoxyphenyl, cyanophenyl, acetamidophenyl,acetylphenyl, and butoxyphenyl).

The cyclic acid anhydride-containing group is a group containing atleast one cyclic acid anhydride. The cyclic acid anhydride to becontained includes an aliphatic dicarboxylic acid anhydride and anaromatic dicarboxylic acid anhydride.

Specific examples of the aliphatic dicarboxylic acid anhydrides includesuccinic anhydride ring, glutaconic anhydride ring, maleic anhydridering, cyclopentane-1,2-dicarboxylic acid anhydride ring,cyclohexane-1,2-dicarboxylic acid anhydride ring,cyclohexene-1,2-dicarboxylic acid anhydride ring, and2,3-bicyclo[2,2,2]octanedicarboxylic acid anhydride. These rings may besubstituted with, for example, a halogen atom such as a chlorine atomand a bromine atom, and an alkyl group such as a methyl group, an ethylgroup, a butyl group and a hexyl group.

Specific examples of the aromatic dicarboxylic acid anhydrides includephthalic anhydride ring, naphthalenedicarboxylic acid anhydride ring,pyridinedicarboxylic acid anhydride ring and thiophenedicarboxylic acidanhydride ring. These rings may be substituted with, for example, ahalogen atom (e.g., chlorine and bromine), an alkyl group (e.g., methyl,ethyl, propyl, and butyl), a hydroxyl group, a cyano group, a nitrogroup, and an alkoxycarbonyl group (e.g., methoxy and ethoxy as thealkoxy group).

In a case wherein the polar group is present in the polymer chain of theresin (A), the polar group may be bonded to the polymer main chaineither directly or via an appropriate linking group. The linking groupcan be any group for connecting the polar group to the polymer mainchain. Specific examples of suitable linking group include ##STR8##(wherein d₁ and d₂, which may be the same or different, each representsa hydrogen atom, a halogen atom (e.g., chlorine, and bromine), ahydroxyl group, a cyano group, an alkyl group (e.g., methyl, ethyl,2-chloroethyl, 2-hydroxyethyl, propyl, butyl, and hexyl), an aralkylgroup (e.g., benzyl, and phenethyl), or a phenyl group), ##STR9##(wherein d₃ and d₄ each has the same meaning as defined for d₁ or d₂above), --C₆ H₁₀, --C₆ H₄ --, --O--, --S--, ##STR10## (wherein d₅represents a hydrogen atom or a hydrocarbon group (preferably havingfrom 1 to 12 carbon atoms (e.g., methyl, ethyl, propyl, butyl, hexyl,octyl, decyl, dodecyl, 2-methoxyethyl, 2-chloroethyl, 2-cyanoethyl,benzyl, methylbenzyl, phenethyl, phenyl, tolyl, chlorophenyl,methoxyphenyl, and butylphenyl)), --CO--, --COO--, --OCO--, --CON(d₅)--,--SO₂ N(d₅)--, --SO₂ --, --NHCONH--, --NHCOO--, --NHSO₂ --, --CONHCOO--,--CONHCONH--, a heterocyclic ring (preferably a 5-membered or 6-memberedring containing at least one of an oxygen atom, a sulfur atom and anitrogen atom as a hetero atom or a condensed ring thereof (e.g.,thiophene, pyridine, furan, imidazole, piperidine, and morpholinerings)), ##STR11## (wherein d₆ and d₇, which may be the same ordifferent, each represents a hydrocarbon group or --Od₈ (wherein d₈represents a hydrocarbon group)), and a combination thereof. Suitableexamples of the hydrocarbon groups include those described for d₅.

The polymer component containing the polar group may be any of specifiedpolar group-containing vinyl compounds copolymerizable with, forexample, a monomer corresponding to the repeating unit represented bythe general formula (I) (including that represented by the generalformula (Ia) or (Ib)). Examples of such vinyl compounds are described,e.g., in Kobunshi Gakkai (ed.), Kobunshi Data Handbook Kisohen (PolymerDate Handbook Basis), Baifukan (1986). Specific examples of these vinylmonomers include acrylic acid, α- and/or β-substituted acrylic acids(e.g., α-acetoxy, α-acetoxymethyl, α-(2-amino)-ethyl, α-chloro, α-bromo,α-fluoro, α-tributylsilyl, α-cyano, β-chloro, β-bromo,α-chloro-β-methoxy, and α,β-dichloro compounds), methacrylic acid,itaconic acid, itaconic half esters, itaconic half amides, crotonicacid, 2-alkenylcarboxylic acids (e.g., 2-pentenoic acid,2-methyl-2-hexenoic acid, 2-octenoic acid, 4-methyl-2-hexenoic acid, and4-ethyl-2-octenoic acid), maleic acid, maleic half esters, maleic halfamides, vinylbenzenecarboxylic acid, vinylbenzenesulfonic acid,vinylsulfonic acid, vinylphosphonic acid, dicarboxylic acid vinyl orallyl half esters, and ester or amide derivatives of these carboxylicacids or sulfonic acids containing the specific polar group in thesubstituent thereof.

Specific examples of the polar group-containing polymer components areset forth below, but the present invention should not be construed asbeing limited thereto. In the following formulae, e₁ represents --H or--CH₃ ; e₂ represents --H, --CH₃ or --CH₂ COOCH₃ ; R₁₄ represents analkyl group having from 1 to 4 carbon atoms; R₁₅ represents an alkylgroup having from 1 to 6 carbon atoms, a benzyl group or a phenyl group;c represents an integer of from 1 to 3; d represents an integer of from2 to 11; e represents an integer of from 1 to 11; f represents aninteger of from 2 to 4; and g represents an integer of from 2 to 10.##STR12##

In such a case, the polar group is included in a component (repeatingunit) for forming the polymer chain of the resin (A) and the polargroups can be present in the resin (A) regularly (in a case of a blockpolymer) or irregularly (in case of a random polymer).

In a case wherein the polar group is present at one terminal of thepolymer chain of the resin (A), the polar group may be bonded to theterminal of the polymer main chain either directly or via an appropriatelinking group. Suitable examples of the linking groups include thoseillustrated for the cases-wherein the polar groups are present in thepolymer chain hereinbefore described.

When the polar group is present at one terminal of polymer main chain ofthe resin (A) as described above, other polar groups are not necessaryto exist in the polymer chain. However, the resin (A) having thespecified polar groups in the polymer chain in addition to the polargroup bonded to the terminal of the main chain is preferable since theelectrostatic characteristics are further improved. The polar groupspresent may be the same or different.

In the resin (A), the ratio of the polar group present in the polymerchain to the polar group bonded to the terminal of the polymer mainchain may be varied depending on the kinds and amounts of other binderresins, a spectral sensitizing dye, a chemical sensitizer and otheradditives which constitute the photoconductive layer according to thepresent invention, and can be appropriately controlled. What isimportant is that the total amount of the polar group-containingcomponent present in the resin (A) is from 0.5 to 15% by weight.

The resin (A) (including resin (A')) according to the present inventionmay further comprise repeating units corresponding to othercopolymerizable monomers as polymer components in addition to therepeating unit of the general formula (I), (Ia) and/or (Ib) and therepeating unit containing the polar group optionally present.

Examples of such monomers include, in addition to methacrylic acidesters, acrylic acid esters and crotonic acid esters containingsubstituents other than those described for the general formula (I),α-olefins, vinyl or allyl esters of carboxylic acids (including, e.g.,acetic acid, propionic acid, butyric acid, valeric acid, benzoic acid,and naphthalenecarboxylic acid, as examples of the carboxylic acids),acrylonitrile, methacrylonitrile, vinyl ethers, itaconic acid esters(e.g., dimethyl ester and diethyl ester), acrylamides, methacrylamides,styrenes (e.g., styrene, vinyltoluene, chlorostyrene, hydroxystyrene,N,N-dimethylaminomethylstyrene, methoxycarbonylstyrene,methanesulfonyloxystyrene, and vinylnaphthalene),vinylsulfone-containing compounds, vinylketone-containing compounds, andheterocyclic vinyl compounds (e.g., vinylpyrrolidone, vinylpyridine,vinylimidazole, vinylthiophene, vinylimidazoline, vinylpyrazoles,vinyldioxane, vinylquinoline, vinyltetrazole, and vinyloxazine). It ispreferred that the content of the polymer components corresponding tosuch other monomers does not exceed 30% by weight of the resin (A).

The resin (A) having the specified polar groups at random in the polymerchain thereof can be easily synthesized according to a conventionallyknown method, for example, a radical polymerization method or an ionpolymerization method using a monomer corresponding to the repeatingunit represented by the general formula (I), a monomer corresponding tothe repeating unit containing the specified polar group and, if desired,other monomers by appropriately selecting the polymerization conditionso as to obtain the resin having the desired molecular weight. A radicalpolymerization method is preferred because purification of the monomersand solvent to be used is unnecessary and a very low polymerizationtemperature such as 0° C. or below is not required. Specifically, apolymerization initiator used includes an azobis type initiator and aperoxide compound each of which is conventionally known. In order tosynthesize the resin having the low molecular weight according to thepresent invention, a known method, for example, increase in the amountof initiator used or regulation of a high polymerization temperature maybe utilized. In general, the amount of initiator used is in a range offrom 0.1 to 20 parts by weight based on the total amount of the monomersemployed, and the polymerization temperature is regulated in a range offrom 30° C. to 200° C. Moreover, a method using a chain transfer agenttogether may be employed. Specifically, a chain transfer agent, forexample, a mercapto compound, or a halogenated compound is used in arange of from 0.01 to 10 parts by weight based on the total amount ofthe monomers employed to adjust the desired weight average molecularweight.

The resin (A) having the specified polar groups as a block in thepolymer chain thereof used in the present invention can be produced by aconventionally known polymerization reaction method. More specifically,it can be produced by the method comprising previously protecting thespecific polar group of a monomer corresponding to the polymer componenthaving the specific polar group to form a functional group, synthesizinga block copolymer by a so-called known living polymerization reaction,for example, an ion polymerization reaction with an organic metalcompound (e.g., alkyl lithiums, lithium diisopropylamide, andalkylmagnesium halides) or a hydrogen iodide/iodine system, aphotopolymerization reaction using a porphyrin metal complex as acatalyst, or a group transfer polymerization reaction, and thenconducting a protection-removing reaction of the functional group whichhad been formed by protecting the polar group by a hydrolysis reaction,a hydrogenolysis reaction, an oxidative decomposition reaction, or aphotodecomposition reaction to form the polar group.

Specifically, the block copolymer can be easily synthesized according tothe synthesis methods described, e.g., in P. Lutz, P. Masson et al,Polym. Bull., 12, 79 (1984), B. C. Anderson, G. D. Andrews et al,Macromolecules, 14, 1601 (1981), K. Hatada, K. Ute et al, Polym. J., 17,977 (1985), ibid., 18, 1037 (1986), Koichi Ute and Koichi Hatada,Kobunshi Kako (Polymer Processing), 36, 366 (1987), ToshinobuHigashimura and Mitsuo Sawamoto, Kobunshi Ronbun Shu (Polymer Treatises,46, 189 (1989), M. Kuroki and T. Aida, J. Am. Chem. Soc., 109, 4737(1989), Teizo Aida and Shohei Inoue, Yuki Gosei Kagaku (OrganicSynthesis Chemistry), 43, 300 (1985), and D. Y. Sogah, W. R. Hertler etal, Macromolecules, 20, 1473 (1987).

Also, the protection of the specific polar group by a protective groupand the release of the protective group (a reaction for removing aprotective group) can be easily conducted by utilizing conventionallyknown knowledges. More specifically, they can be performed byappropriately selecting methods described, e.g., in Yoshio Iwakura andKeisuke Kurita, Hannosei Kobunshi (Reactive Polymer), Kodansha (1977),T. W. Greene, Protective Groups in Organic Synthesis, John Wiley & Sons(1981), and J. F. W. McOmie, Protective Groups in Organic Chemistry,Plenum Press, (1973), as well as the methods as described in the abovereferences.

Further, the resin (A) containing the polar group as a block can also besynthesized by performing a polymerization reaction under lightirradiation using a monomer having an unprotected polar group and alsousing a dithiocarbamate group-containing compound and/or xanthategroup-containing compound as an initiator. For example, the blockcopolymer can be synthesized according to the synthesis methodsdescribed, e.g., in Takayuki Otsu, Kobunshi (Polymer), 37, 248 (1988),Shunichi Himori and Ryuichi Otsu, Polym. Rep. Jap. 37, 3508 (1988),JP-A-64-111, JP-A-64-26619, Nobuyuki Higashi et al, Polymer PreprintsJapan, 36, (6), 1511 (1987), and M. Niwa, N. Higashi et al, J. Macromol.Sci. Chem., A24, (5), 567 (1987).

The resin ( A ) according to the present invention, in which thespecific polar group is bonded to only one terminal of the polymer mainchain, can easily be prepared by an ion polymerization process, in whicha various kind of reagents is reacted at the terminal of a livingpolymer obtained by conventionally known anion polymerization or cationpolymerization; a radical polymerization process, in which radicalpolymerization is performed in the presence of a polymerizationinitiator and/or a chain transfer agent which contains the specificpolar group in the molecule thereof; or a process, in which a polymerhaving a reactive group (for example, an amino group, a halogen atom, anepoxy group, and an acid halide group) at the terminal obtained by theabove-described ion polymerization or radical polymerization issubjected to a polymer reaction to convert the terminal reactive groupinto the specific polar group.

More specifically, reference can be made to, e.g., P. Dreyfuss and R. P.Quirk, Encycl. Polym. Sci. Eng., 7, 551 (1987), Yoshiki Nakajo and YuyaYamashita, Senryo to Yakuhin (Dyes and Chemicals), 30, 232 (1985), AkiraUeda and Susumu Nagai, Kagaku to Kogyo (Science and Industry), 60, 57(1986) and literature references cited therein.

Specific examples of chain transfer agents which can be used includemercapto compounds containing the polar group or the reactive groupcapable of being converted into the polar group (e.g., thioglycolicacid, thiomalic acid, thiosalicylic acid, 2-mercaptopropionic acid,3-mercaptopropionic acid, 3-mercaptobutyric acid,N-(2-mercaptopropionyl)glycine, 2-mercaptonicotinic acid,3-[N-(2-mercaptoethyl)carbamoyl]propionic acid,3-[N-(2-mercaptoethyl)amino]propionic acid,N-(3-mercaptopropionyl)alanine, 2-mercaptoethanesulfonic acid,3-mercaptopropanesulfonic acid, 4-mecaptobutanesulfonic acid,2-mercaptoethanol, 3-mercapto-1,2-propanediol, 1-mercapto-2-propanol,3-mercapto-2-butanol, mercaptophenol, 2-mercaptoethylamine,2-mercaptoimidazole, 2-mercapto-3-pyridinol,4-(2-mercaptoethyloxycarbonyl)phthalic acid anhydride,2-mercaptoethylphosphonic acid anhydride, and monomethyl2-mercaptoethylphosphonate), and alkyl iodide compounds containing thepolar group or the polar group-forming reactive group (e.g., iodoaceticacid, iodopropionic acid, 2-iodoethanol, 2-iodoethanesulfonic acid, and3-iodopropanesulfonic acid).

Specific examples of the polymerization initiators containing the polargroup or the reactive group include 4,4'-azobis(4-cyanovaleric acid),4,4'-azobis(4-cyanovaleric acid chloride), 2,2'-azobis(2-cyanopropanol),2,2'-azobis(2-cyanopentanol),2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide],2,2'-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide},2,2'-azobis{2-[1-(2-hydroxyethyl)-2-imidazolin-2-yl]propane},2,2'-azobis[2-(2-imidazolin-2-yl)propane], and2,2'-azobis[2-(4,5,6,7-tetrahydro-1H-1,3-diazepin-2-yl)propane].

The chain transfer agent or polymerization initiator is usually used inan amount of from 0.5 to 15 parts by weight, preferably from 2 to 10parts by weight, per 100 parts by weight of the total monomers used.

Further, the resin (A) having the specific polar group at the terminalof the polymer main chain can be produced by a photopolymerizationmethod using a dithiocarbamate group-containing compound or xanthategroup-containing compound containing as a substituent the specific polargroup, as a photo-initiator. Specifically, it can be easily preparedaccording to a method described, e.g., in Takayuki Otsu, Kobunshi(Polymer), 37, 248 (1988), Shunichi Himori and Ryuichi Ohtsu, Polym.Rep. Jap. 37, 3508 (1988), JP-A-64-111, JP-A-64-26619, Nobuyuki Higashiet al, Polymer Preprints Japan, 36, (6), 1511 (1987), and M. Niwa, N.Higashi et al, J. Macromol. Sci. Chem., A24, (5), 567 (1987).

Examples of the dithiocarbamate group- or xanthate group-containingcompound include those represented by the general formula (PI) or (PII)described below. ##STR13## wherein R²³, R²⁴, R²⁵, R²⁶ and R²⁷ eachrepresents a hydrocarbon group and at least one of R²³, R²⁴ and R²⁵ orat least one of R²⁶ and R²⁷ contains at least one of the above describedspecific polar groups as a substituent. Specific examples of thehydrocarbon group include those described for R³ in the general formula(I) described above.

Now, the resin (B) which can be used as the binder resin for thephotoconductive layer of the electrophotographic light-sensitivematerial according to the present invention will be described in moredetail below.

The resin (B) is a starlike polymer comprising an organic moleculehaving bonded thereto at least three polymer chains each containing apolymer component containing the specified polar group and a polymercomponent corresponding to a repeating unit represented by the generalformula (I).

For instance, the starlike polymer according to the present inventioncan be schematically illustrated below. ##STR14## wherein X representsan organic molecule, and [Polymer] represents a polymer chain.

In the starlike polymer, three or more polymer chains which are bondedto the organic molecule may be the same as or different from each otherin their structures, and the length of each polymer chain may be thesame or different.

As described above, the polymer chain comprises at least one polymercomponent containing the specified polar group and at least one polymercomponent represented by the general formula (I), and the composition ofthe polymer chain may include various embodiments. Specifically, thespecified polar group-containing components and the componentsrepresented by the general formula (I) each constituting the polymerchain may be present at random or as a block.

In the latter case, the resin (B) is a starlike polymer comprising anorganic molecule having bonded thereto at least three AB block polymerchains each containing an A block comprising a polymer componentcontaining the specified polar group and a B block comprising a polymercomponent represented by the general formula (I). The B block does notcontain any specified polar group included in the A block. The A blockand the B block in the polymer chain can be arranged in any order. Sucha type of the resin (B) can, for example, be schematically illustratedbelow. ##STR15## wherein X represents an organic molecule, (A)represents an A block, (B) represents a B block, and (A)--(B) representsa polymer chain.

In another embodiment, the polymer chain in the resin (B) may have oneof the above described specified polar group bonded at the terminalthereof opposite to the terminal at which the polymer chain is bonded tothe organic molecule. In such a case, the resin (B) is a starlikepolymer comprising an organic molecule having bonded thereto at leastthree polymer chains each containing at least a polymer componentrepresented by the general formula (I) and having the specified polargroup bonded at the terminal thereof opposite to the terminal at whichthe polymer chain is bonded to the organic molecule. Such a type of theresin (B) can, for example, be schematically illustrated below.##STR16## wherein X represents an organic molecule, [Polymer] representsa polymer chain, (A) represents an A block, (B) represents a B block,(A)--(B) represents a polymer chain; and W represents a specified polargroup.

Particularly, the resin (B) wherein the polymer chain comprises the Bblock and the A block and the specified polar group is bonded at theterminal of the A block as described in (B-6) above is preferred in viewof providing more improved electrostatic characteristics.

In the starlike polymer of the resin (B), a number of the polymer chainsbonded to an organic molecule is at most 15, and usually about 10 orless.

The resin (B) is characterized by containing from 0.01 to 10% by weightof polymer component containing the specified polar group and not lessthan 30% by weight of polymer component represented by the generalformula (I) bases on the resin (B) as described above.

If the content of the polar group-containing component in the resin (B)is less than 0.01% by weight, the initial potential is low and thussatisfactory image density can not be obtained. On the other hand, ifthe content of the polar group-containing component is larger than 10%by weight, various undesirable problems may occur, for example, thedispersibility of particles of photoconductive substance is reduced, thefilm smoothness and the electrophotographic characteristics under hightemperature and high humidity condition deteriorate, and further whenthe light-sensitive material is used as an offset master plate, theoccurrence of background stains increases. The amount of the polargroup-containing component in the resin (B) is preferably from 0.05 to8% by weight.

It is also preferred that the total amount of the specified polargroup-containing polymer component contained in the resin (B) is from 10to 50% by weight based on the total amount of the specified polargroup-containing polymer component present in the resin (A).

If the total amount of the specified polar group-containing component inthe resin (B) is less than 10% by weight of that in the resin (A), theelectrophotographic characteristics (particularly, dark charge retentionrate and photosensitivity) and film strength tend to decrease. On theother hand, if it is larger than 50% by weight, a sufficiently uniformdispersion of particles of photoconductive substance may not beobtained, whereby the electrophotographic characteristics decrease andwater retentivity decline when used as an offset master plate.

The content of the polymer component represented by the general formula(I) in the resin (B) is preferably not less than 50% by weight.

The weight average molecular weight of the resin (B) is from 3×10⁴ to1×10⁶, and preferably from 5×10⁴ to 5×10⁵. If the weight averagemolecular weight of the resin (B) is less than 3×10⁴, the film-formingproperty of the resin is lowered, whereby a sufficient film strengthcannot be maintained, while if the weight average molecular weight ofthe resin (B) is higher than 1×10⁶, the effect of the resin (B) of thepresent invention is reduced, whereby the electrophotographiccharacteristics thereof become almost the same as those ofconventionally known resins.

The glass transition point of the resin (B) is preferably from -10° C.to 100° C., and more preferably from 0° C. to 90° C.

The polymer component having the specified polar group (including thatpresent in the polymer chain and/or at the terminal of the polymerchain) and the polymer component represented by the general formula (I)are the same as those described in detail for the resin (A)hereinbefore.

The resin (B) may contain polymer components other than the polymercomponents descrived above. Examples of such other polymer componentspreferably include those corresponding to the repeating unit representedby the following general formula (II): ##STR17## wherein D¹ represents--COO--, --OCO--, .paren open-st.CH₂ .paren close-st._(k) --OCO--,.paren open-st.CH₂ .paren close-st._(k) --COO--, --O--, --SO₂ --,--CO--, ##STR18## --CONHCOO--, --CONHCONH-- or ##STR19## (wherein krepresents an integer of from 1 to 3; and D³ represents a hydrogen atomor a hydrocarbon group); D² represents a hydrocarbon group; and m¹ andm², which may be the same or different, each has the same meaning as a¹or a² in the general formula (I) described above.

Preferred examples of the hydrocarbon group represented by D³ include analkyl group having from 1 to 18 carbon atoms which may be substituted(e.g., methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl,decyl, dodecyl, hexadecyl, octadecyl, 2-chloroethyl, 2-bromoethyl,2-cyanoethyl, 2-methoxycarbonylethyl, 2-methoxyethyl, and3-bromopropyl), an alkenyl group having from 4 to 18 carbon atoms whichmay be substituted (e.g., 2-methyl-1-propenyl, 2-butenyl, 2-pentenyl,3-methyl-2-pentenyl, 1-pentenyl, 1-hexenyl, 2-hexenyl, and4-methyl-2-hexenyl), an aralkyl group having from 7 to 12 carbon atomswhich may be substituted (e.g., benzyl, phenethyl, 3-phenylpropyl,naphthylmethyl, 2-naphthylethyl, chlorobenzyl, bromobenzyl,methylbenzyl, ethylbenzyl, methoxybenzyl, dimethylbenzyl, anddimethoxybenzyl), an alicyclic group having from 5 to 8 carbon atomswhich may be substituted (e.g., cyclohexyl, 2-cyclohexylethyl, and2-cyclopentylethyl), and an aromatic group having from 6 to 12 carbonatoms which may be substituted (e.g., phenyl, naphthyl, tolyl, xylyl,propylphenyl, butylphenyl, octylphenyl, dodecylphenyl, methoxyphenyl,ethoxyphenyl, butoxyphenyl, decyloxyphenyl, chlorophenyl,dichlorophenyl, bromophenyl, cyanophenyl, acetylphenyl,methoxycarbonylphenyl, ethoxycarbonylphenyl, butoxycarbonylphenyl,acetamidophenyl, propioamidophenyl, and dodecyloylamidophenyl).

When D¹ represents ##STR20## the benzene ring may be substituted.Suitable examples of the substituents include a halogen atom (e.g.,chlorine, and bromine), an alkyl group (e.g., methyl, ethyl, propyl,butyl, chloromethyl, and methoxymethyl), and an alkoxy group (e.g.,methoxy, ethoxy, propoxy, and butoxy).

Preferred examples of the hydrocarbon group represented by D² include analkyl group having from 1 to 22 carbon atoms which may be substituted(e.g., methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl,decyl, dodecyl, tridecyl, tetradecyl, hexadecyl, octadecyl,2-chloroethyl, 2-bromoethyl, 2-cyanoethyl, 2-methoxycarbonylethyl,2-methoxyethyl, and 3-bromopropyl), an alkenyl group having from 4 to 18carbon atoms which may be substituted (e.g., 2-methyl-1-propenyl,2-butenyl, 2-pentenyl, 3-methyl-2-pentenyl, 1-pentenyl, 1-hexenyl,2-hexenyl, and 4-methyl-2-hexenyl), an aralkyl group having from 7 to 12carbon atoms which may be substituted (e.g., benzyl, phenethyl,3-phenylpropyl, naphthylmethyl, 2-naphthylethyl, chlorobenzyl,bromobenzyl, methylbenzyl, ethylbenzyl, methoxybenzyl, dimethylbenzyl,and dimethoxybenzyl), an alicyclic group having from 5 to 8 carbon atomswhich may be substituted (e.g., cyclohexyl, 2-cyclohexylethyl, and2-cyclopentylethyl), and an aromatic group having from 6 to 12 carbonatoms which may be substituted (e.g., phenyl, naphthyl, tolyl, xylyl,propylphenyl, butylphenyl, octylphenyl, dodecylphenyl, methoxyphenyl,ethoxyphenyl, butoxyphenyl, decyloxyphenyl, chlorophenyl,dichlorophenyl, bromophenyl, cyanophenyl, acetylphenyl,methoxycarbonylphenyl, ethoxycarbonylphenyl, butoxycarbonylphenyl,acetamidophenyl, propioamidophenyl, and dodecyloylamidophenyl).

More preferably, in the general formula (II), D¹ represents --COO--,--OCO--, --CH₂ OCO--, --CH₂ COO--, --O--, --CONH--, --SO₂ NH-- or##STR21##

Moreover, the resin (B) may further contain other polymer componentscorresponding to monomers copolymerizable with monomers corresponding tothe polymer components represented by the general formula (II). Examplesof such monomers include acrylonitrile, methacrylonitrile andheterocyclic vinyl compounds (e.g., vinylpyridine, vinylimidazole,vinylpyrrolidone, vinylthiophene, vinylpyrazoles, vinyldioxane andvinyloxazine). However, such other monomers are preferably employed inan amount of not more than 20 parts by weight per 100 parts by weight ofthe resin (B).

The organic molecule to which at least three polymer chains are bondedand which is used in the resin (B) according to the present invention isany organic molecule having a molecular weight of 1000 or less. Suitableexamples of the organic molecules include those containing a trivalentor more hydrocarbon moiety shown below. ##STR22## wherein ( ) representsa repeating unit; r¹, r², r³ and r⁴ each represents a hydrogen atom or ahydrocarbon group, provided that at least one of r¹ and r² or r³ and r⁴is bonded to a polymer chain.

These organic moieties may be employed individually or as a combinationthereof. In the latter case, the combination may further contain anappropriate linking unit, for example, --O--, --S--, ##STR23## (whereinr⁷ represents a hydrogen atom or a hydrocarbon group), --CO--, --CS--,--COO--, ##STR24## --NHCOO--, --NHCONH-- and a heterocyclic groupcontaining at least one hetero atom such as oxygen, sulfur or nitrogen(e.g., thiophene, pyridine, pyran, imidazole, benzimidazole, furan,piperidine, pyrazine, pyrrole and piperazine, as the hetero ring).

Other examples of the organic molecules to which the polymer chains arebonded include those comprising a combination of ##STR25## with alinking unit described above. However, the organic molecules which canbe used in the present invention should not be construed as beinglimited to those described above.

The starlike polymer according to the present invention can be preparedby utilizing conventionally known synthesis methods of starlike polymersusing monomers containing a polar group and a polymerizable double bondgroup. For instance, a method of polymerization reaction using acarboanion as an initiator can be employed. Such a method isspecifically described in M. Morton, T. E. Helminiak et al, J. Polym.Sci., 57, 471 (1962), B. Gordon III, M. Blumenthal, J. E. Loftus, et alPolym. Bull., 11, 349 (1984), and R. B. Bates, W. A. Beavers, et al, J.Org. Chem., 44, 3800 (1979). In case of using the reaction, it isrequired that the specified polar group be protected to form afunctional group and the protective group be removed afterpolymerization.

The protection of the specified polar group of the present invention bya protective group and the release of the protective group (a reactionfor removing a protective group) can be easily conducted by utilizingconventionally known knowledges. More specifically, they can beperformed by appropriately selecting methods described, e.g., in YoshioIwakura and Keisuke Kurita, Hannosei Kobunshi (Reactive Polymer),Kodansha (1977), T. W. Greene, Protective Groups in Organic Synthesis,John Wiley & Sons (1981), and J. F. W. McOmie, Protective Groups inOrganic Chemistry, Plenum Press, (1973), as well as methods as describedin the above references.

Further, in another method, the polymer can be synthesized by conductinga polymerization reaction under light irradiation using a monomer havingthe unprotected polar group and also using a dithiocarbamategroup-containing compound and/or a xanthate group-containing compound asan initiator. For example, copolymer can be synthesized according to thesynthesis methods described, e.g., in Takayuki Otsu, Kobunshi (Polymer),37, 248 (1988), Shunichi Himori and Ryichi Otsu, Polym. Rep. Jap. 37,3508 (1988), JP-A-64-111, JP-A-64-26619, Nobuyuki Higashi et al, PolymerPreprints Japan, 36 (6) 1511 (1987), and M. Niwa, N. Higashi et al, J.Macromol. Sci. Chem., A24(5), 567 (1987).

The ratio of resin (A) to resin (B) used in the present invention ispreferably 0.05 to 0.60/0.95 to 0.40, more preferably 0.10 to 0.40/0.90to 0.60 in terms of a weight ratio of resin (A)/resin (B).

When the weight ratio of resin (A)/resin (B) is less than 0.05, theeffect for improving the electrostatic characteristics may be reduced.On the other hand, when it is more than 0.60, the film strength of thephotoconductive layer may not be sufficiently maintained in some cases(particularly, in case of using as an electrophotographic printing plateprecursor).

Furthermore, in the present invention, the binder resin used in thephotoconductive layer may contain other resin(s) known for inorganicphotoconductive substance in addition to the resin (A) and the resin (B)according to the present invention. However, the amount of other resinsdescried above should not exceed 30% parts by weight per 100 parts byweight of the total binder resins since, if the amount is more than 30parts by weight, the effects of the present invention are remarkablyreduced.

Representative other resins which can be employed together with theresins (A) and (B) according to the present invention include vinylchloride-vinyl acetate copolymers, styrene-butadiene copolymers,styrene-methacrylate copolymers, methacrylate copolymers, acrylatecopolymers, vinyl acetate copolymers, polyvinyl butyral resins, alkydresins, silicone resins, epoxy resins, epoxyester resins, and polyesterresins.

Specific examples of other resins used are described, for example, inTakaharu Shibata and Jiro Ishiwatari, Kobunshi (High MolecularMaterials), 17, 278 (1968), Harumi Miyamoto and Hidehiko Takei, ImagingNo. 8, 9 (1973), Koichi Nakamura, Kiroku Zairyoyo Binder no JissaiGijutsu (Practical Technique of Binders for Recording Materials), Cp.10, published by C. M. C. Shuppan (1985), D. Tatt, S. C. HeideckerTappi, 49, No. 10, 439 (1966), E. S. Baltazzi, R. G. Blanckette, et al.,Photo. Sci. Eng., 16, No. 5, 354 (1972), Nguyen Chank Keh, Isamu Shimizuand Eiichi Inoue, Denshi Shashin Gakkaishi (Journal ofElectrophotographic Association), 18, No. 2, 22 (1980), JP-B-50-31011,JP-A-53-54027, JP-A-54-20735, JP-A-57-202544 and JP-A-58-68046.

The total amount of binder resin used in the photoconductive layeraccording to the present invention is preferably from 10 to 100 parts byweight, more preferably from 15 to 50 parts by weight, per 100 parts byweight of the inorganic photoconductive substance.

When the total amount of binder resin used is less than 10 parts byweight, it may be difficult to maintain the film strength of thephotoconductive layer. On the other hand, when it is more than 100 partsby weight, the electrostatic characteristics may decrease and the imageforming performance may degrade to result in the formation of poorduplicated image.

The inorganic photoconductive substance which can be used in the presentinvention includes zinc oxide, titanium oxide, zinc sulfide, cadmiumsulfide, cadmium carbonate, zinc selenide, cadmium selenide, telluriumselenide, and lead sulfide.

As the spectral sensitizing dye according to the present invention,various dyes can be employed individually or as a combination of two ormore thereof. Examples of the spectral sensitizing dyes are carboniumdyes, diphenylmethane dyes, triphenylmethane dyes, xanthene dyes,phthalein dyes, polymethine dyes (e.g., oxonol dyes, merocyanine dyes,cyanine dyes, rhodacyanine dyes, and styryl dyes), and phthalocyaninedyes (including metallized dyes). Reference can be made to, for example,in Harumi Miyamoto and Hidehiko Takei, Imaging, 1973, No. 8, 12, C. J.Young et al., RCA Review, 15, 469 (1954), Kohei Kiyota et al.,Denkitsushin Gakkai Ronbunshi, J 63-C, No. 2, 97 (1980), Yuji Harasakiet al., Kogyo Kagaku Zasshi, 66, 78 and 188 (1963), and Tadaaki Tani,Nihon Shashin Gakkaishi, 35, 208 (1972).

Specific examples of the carbonium dyes, triphenylmethane dyes, xanthenedyes, and phthalein dyes are described, for example, in JP-B-51-452,JP-A-50-90334, JP-A-50-114227, JP-A-53-39130, JP-A-53-82353, U.S. Pat.Nos. 3,052,540 and 4,054,450, and JP-A-57-16456.

The polymethine dyes, such as oxonol dyes, merocyanine dyes, cyaninedyes, and rhodacyanine dyes, include those described, for example, in F.M. Hamer, The Cyanine Dyes and Related Compounds. Specific examplesinclude those described, for example, in U.S. Pat. Nos. 3,047,384,3,110,591, 3,121,008, 3,125,447, 3,128,179, 3,132,942, and 3,622,317,British Patents 1,226,892, 1,309,274 and 1,405,898, JP-B-48-7814 andJP-B-55-18892.

In addition, polymethine dyes capable of spectrally sensitizing in thelonger wavelength region of 700 nm or more, i.e., from the near infraredregion to the infrared region, include those described, for example, inJP-A-47-840, JP-A-47-44180, JP-B-51-41061, JP-A-49-5034, JP-A-49-45122,JP-A-57-46245, JP-A-56-35141, JP-A-57-157254, JP-A-61-26044,JP-A-61-27551, U.S. Pat. Nos. 3,619,154 and 4,175,956, and Researchdisclosure, 216, 117 to 118 (1982).

The electrophotographic light-sensitive material of the presentinvention is excellent in that the performance properties thereof arenot liable to vary even when various kinds of sensitizing dyes areemployed together.

If desired, the photoconductive layer may further contain variousadditives commonly employed in conventional electrophotographiclight-sensitive layer, such as chemical sensitizers. Examples of suchadditives include electron-accepting compounds (e.g., halogen,benzoquinone, chloranil, acid anhydrides, and organic carboxylic acids )as described in the above-mentioned Imaging, 1973, No. 8, 12; andpolyarylalkane compounds, hindered phenol compounds, andp-phenylenediamine compounds as described in Hiroshi Kokado et al.,Saikin-no Kododen Zairyo to Kankotai no Kaihatsu Jitsuyoka, Chaps. 4 to6, Nippon Kagaku Joho K.K. (1986).

The amount of these additives is not particularly restricted and usuallyranges from 0.0001 to 2.0 parts by weight per 100 parts by weight of thephotoconductive substance.

The photoconductive layer suitably has a thickness of from 1 to 100 μm,preferably from 10 to 50 μm.

In cases where the photoconductive layer functions as a chargegenerating layer in a laminated light-sensitive material composed of acharge generating layer and a charge transporting layer, the thicknessof the charge generating layer suitably ranges from 0.01 to 1 μm,preferably from 0.05 to 0.5 μm.

If desired, an insulating layer can be provided on the light-sensitivelayer of the present invention. When the insulating layer is made toserve for the main purposes for protection and improvement of durabilityand dark decay characteristics of the light-sensitive material, itsthickness is relatively small. When the insulating layer is formed toprovide the light-sensitive material suitable for application to specialelectrophotographic processes, its thickness is relatively large,usually ranging from 5 to 70 μm, preferably from 10 to 50 μm.

Charge transporting materials in the above-described laminatedlight-sensitive material include polyvinylcarbazole, oxazole dyes,pyrazoline dyes, and triphenylmethane dyes. The thickness of the chargetransporting layer ranges usually from 5 to 40 μm, preferably from 10 to30 μm.

Resins to be used in the insulating layer or charge transporting layertypically include thermoplastic and thermosetting resins, e.g.,polystyrene resins, polyester resins, cellulose resins, polyetherresins, vinyl chloride resins, vinyl acetate resins, vinylchloride-vinyl acetate copolymer resins, polyacrylate resins, polyolefinresins, urethane resins, epoxy resins, melamine resins, and siliconeresins.

The photoconductive layer according to the present invention can beprovided on any known support. In general, a support for anelectrophotographic light-sensitive layer is preferably electricallyconductive. Any of conventionally employed conductive supports may beutilized in the present invention. Examples of usable conductivesupports include a substrate (e.g., a metal sheet, paper, and a plasticsheet) having been rendered electrically conductive by, for example,impregnating with a low resistant substance; the above-describedsubstrate with the back side thereof (opposite to the light-sensitivelayer side) being rendered conductive and having further coated thereonat least one layer for the purpose of prevention of curling; theabove-described substrate having provided thereon a water-resistantadhesive layer; the above-described substrate having provided thereon atleast one precoat layer; and paper laminated with a conductive plasticfilm on which aluminum is vapor deposited.

Specific examples of conductive supports and materials for impartingconductivity are described, for example, in Yukio Sakamoto,Denshishashin, 14, No. 1, pp. 2 to 11 (1975), Hiroyuki Moriga, NyumonTokushushi no Kagaku, Kobunshi Kankokai (1975), and M. F. Hoover, J.Macromol. Sci. Chem., A-4(6), pp. 1327 to 1417 (1970).

The electrophotographic light-sensitive material according to thepresent invention can be utilized in any known electrophotographicprocess. Specifically, the light-sensitive material of the presentinvention is employed in any recording system including a PPC system anda CPC system in combination with any developer including a dry typedeveloper and a liquid developer. In particular, the light-sensitivematerial is preferably employed in combination with a liquid developerin order to obtain the excellent effect of the present invention sincethe light-sensitive material is capable of providing faithfullyduplicated image of highly accurate original.

Further, a color duplicated image can be produced by using it incombination with a color developer in addition to the formation of blackand white image. Reference can be made to methods described, forexample, in Kuro Takizawa, Shashin Kogyo, 33, 34 (1975) and MasayasuAnzai, Denshitsushin Gakkai Gijutsu Kenkyu Hokoku, 77, 17 (1977).

Moreover, the light-sensitive material of the present invention iseffective for recent other systems utilizing an electrophotographicprocess. For instance, the light-sensitive material containingphotoconductive zinc oxide as a photoconductive substance is employed asan offset printing plate precursor, and the light-sensitive materialcontaining photoconductive zinc oxide or titanium oxide which does notcause environmental pollution and has good whiteness is employed as arecording material for forming a block copy usable in an offset printingprocess or a color proof.

BEST MODE FOR CONDUCTING THE INVENTION

The present invention is illustrated in greater detail with reference tothe following examples, but the present invention is not to be construedas being limited thereto.

Synthesis examples of the resin (A) are specifically illustrated below.

SYNTHESIS EXAMPLE 1 OF RESIN (A) Resin (A-1)

A mixed solution of 95 g of benzyl methacrylate, 5 g of acrylic acid,and 200 g of toluene was heated to 90° C. under nitrogen gas stream, and6.0 g of 2,2'-azobisisobutyronitrile (abbreviated as AIBN) was addedthereto to effect a reaction for 4 hours. To the reaction mixture wasfurther added 2 g of AIBN, followed by reacting for 2 hours. Theresulting resin (A-1) had a weight average molecular weight (Mw) of8,500. The weight average molecular weight (Mw) was a value measured bythe GPC method and calculated in terms of polystyrene (hereinafter thesame). ##STR26##

SYNTHESIS EXAMPLES 2 TO 28 OF RESIN (A) Resins (A-2) to (A-28)

Each of Resins (A-2) to (A-28) shown in Table 1 below was synthesizedunder the same polymerization conditions as described in SynthesisExample 1 of Resin (A). A weight average molecular weight of each of theresins (A) was in a range of from 5.0×10³ to 9.0×10³.

                                      TABLE 1                                     __________________________________________________________________________     ##STR27##                                                                    Synthesis                                           x/y                       Example of                                          (weight                   Resin (A)                                                                           Resin (A)                                                                           R.sub.14         Y.sub.1                ratio)                    __________________________________________________________________________    2     A-2   CH.sub.2 C.sub.6 H.sub.5                                                                        ##STR28##             94/6                      3     A-3                                                                                  ##STR29##                                                                                      ##STR30##             95/5                      4     A-4   C.sub.6 H.sub.5                                                                                 ##STR31##             95/5                      5     A-5   CH.sub.2 C.sub.6 H.sub.5                                                                        ##STR32##             97/3                      6     A-6                                                                                  ##STR33##                                                                                      ##STR34##             95/5                      7     A-7                                                                                  ##STR35##                                                                                      ##STR36##             94/6                      8     A-8                                                                                  ##STR37##                                                                                      ##STR38##             95/5                      9     A-9   CH.sub.2 C.sub.6 H.sub.5                                                                        ##STR39##             93/7                      10    A-10                                                                                 ##STR40##                                                                                      ##STR41##             95/5                      11    A-11                                                                                 ##STR42##                                                                                      ##STR43##             96/4                      12    A-12                                                                                 ##STR44##                                                                                      ##STR45##             97/3                      13    A-13                                                                                 ##STR46##                                                                                      ##STR47##             97/3                      14    A-14                                                                                 ##STR48##                                                                                      ##STR49##             94/6                      15    A-15                                                                                 ##STR50##                                                                                      ##STR51##             97/3                      16    A-16                                                                                 ##STR52##                                                                                      ##STR53##             95/5                      17    A-17                                                                                 ##STR54##                                                                                      ##STR55##             93/7                      18    A-18                                                                                 ##STR56##                                                                                      ##STR57##             97/3                      19    A-19                                                                                 ##STR58##                                                                                      ##STR59##             95/5                      20    A-20                                                                                 ##STR60##                                                                                      ##STR61##             98/2                      21    A-21                                                                                 ##STR62##                                                                                      ##STR63##             96/4                      22    A-22  CH.sub.2 C.sub.6 H.sub.5                                                                        ##STR64##             97/3                      23    A-23                                                                                 ##STR65##                                                                                      ##STR66##             94/6                      24    A-24                                                                                 ##STR67##                                                                                      ##STR68##             95/5                      25    A-25                                                                                 ##STR69##                                                                                      ##STR70##             92/8                      26    A-26                                                                                 ##STR71##                                                                                      ##STR72##             97/3                      27    A-27                                                                                 ##STR73##                                                                                      ##STR74##             95/5                      28    A-28                                                                                 ##STR75##                                                                                      ##STR76##             95/5                      __________________________________________________________________________

SYNTHESIS EXAMPLE 29 OF RESIN (A) Resin (A-29)

A mixed solution of 95 g of 2,6-dichlorophenyl methacrylate, 5 g ofacrylic acid, 2 g of n-dodecylmercaptan, and 200 g of toluene was heatedto a temperature of 80° C. under nitrogen gas stream, and 2 g of AIBNwas added thereto to effect reaction for 4 hours. Then, 0.5 g of AIBNwas added thereto, followed by reacting for 2 hours, and thereafter 0.5g of AIBN was added thereto, followed by reacting for 3 hours. Aftercooling, the reaction mixture was poured into 2 liters of a solventmixture of methanol and water (9:1) to reprecipitate, and theprecipitate was collected by decantation and dried under reducedpressure to obtain 78 g of the copolymer in the wax form having a weightaverage molecular weight of 6.3×10³.

SYNTHESIS EXAMPLES 30 TO 33 OF RESIN (A) Resins (A-30) to (A-33)

Copolymers shown in Table 2 below were synthesized in the same manner asdescribed in Synthesis Example 29 of Resin (A), respectively. A weightaverage molecular weight of each of the polymers was in a range of from6×10³ to 8×10³.

                  TABLE 2                                                         ______________________________________                                         ##STR77##                                                                    Synthesis                           x/y                                       Example of                                                                            Resin                       (weight                                   Resin (A)                                                                             (A)      Y                  ratio)                                    ______________________________________                                        30      A-30                                                                                    ##STR78##         90/5                                      31      A-31                                                                                    ##STR79##         92/3                                      32      A-32                                                                                    ##STR80##         88/7                                      33      A-33                                                                                    ##STR81##         90/5                                      ______________________________________                                    

SYNTHESIS EXAMPLE 101 OF RESIN (A) Resin (A-101)

A mixed solution of 96 g of benzyl methacrylate, 4 g of thiosalicylicacid, and 200 g of toluene was heated to a temperature of 75° C. undernitrogen gas stream, and 1.0 g of 2,2'-azobisisobutyronitrile(abbreviated as AIBN) was added thereto to effect reaction for 4 hours.To the reaction mixture was further added 0.4 g of AIBN, followed bystirring for 2 hours, and thereafter 0.2 g of AIBN was added thereto,followed by stirring for 3 hours. The resulting resin (A-101) had thefollowing structure and a weight average molecular weight of 6.8×10³.##STR82##

SYNTHESIS EXAMPLES 102 TO 113 OF RESIN (A) Resins (A-102) to (A-113)

Resins (A-102) to (A-113) were synthesized in the same manner asdescribed in Synthesis Example 101 of Resin (A), except for using themonomers described in Table 3 below in place of 96 g of benzylmethacrylate, respectively. A weight average molecular weight of each ofthese resins was in a range of from 6.0×10³ to 8×10³.

                                      TABLE 3                                     __________________________________________________________________________     ##STR83##                                                                    Synthesis                                      x/y                            Example of                                     (weight                        Resin (A)                                                                           Resin (A)                                                                           R.sub.17       Y.sub.1             ratio)                         __________________________________________________________________________    102   A-102 C.sub.2 H.sub.5                                                                               ##STR84##          94/2                           103   A-103 C.sub.6 H.sub.5                                                                               ##STR85##          94/2                           104   A-104                                                                                ##STR86##                                                                                    ##STR87##          94.5/1.5                       105   A-105                                                                                ##STR88##                                                                                    ##STR89##          94/2                           106   A-106 CH.sub.2 C.sub.6 H.sub.5                                                                      ##STR90##          93.5/2.5                       107   A-107 C.sub.2 H.sub.5                                                                               ##STR91##          93/3                           108   A-108                                                                                ##STR92##                                                                                    ##STR93##          85/11                          109   A-109                                                                                ##STR94##     --                  96/0                           110   A-110                                                                                ##STR95##                                                                                    ##STR96##          92/4                           111   A-111                                                                                ##STR97##                                                                                    ##STR98##          94.5/1.5                       112   A-112                                                                                ##STR99##                                                                                    ##STR100##         76/20                          113   A-113 (CH.sub.2).sub.2OC.sub.6 H.sub.5                                                             --                  96/0                           __________________________________________________________________________

SYNTHESIS EXAMPLES 114 TO 124 OF RESIN (A) Resins (A-114) to (A-124)

Resins (A-114) to (A-124) were synthesized under the same reactionconditions as described in Synthesis Example 101 of Resin (A), exceptfor using the methacrylates and mercapto compounds described in Table 4below in place of 96 g of benzyl methacrylate and 4 g of thiosalicylicacid and replacing 200 g of toluene with 150 g of toluene and 50 g ofisopropanol, respectively.

                                      TABLE 4                                     __________________________________________________________________________     ##STR101##                                                                   Synthesis                                                                     Example of                                            Weight Average          Resin (A)                                                                            Resin (A)                                                                           W                   Amount                                                                             R.sub.18   Amount                                                                             Molecular               __________________________________________________________________________                                                          Weight                  114    A-114 HOOCCH.sub.2 CH.sub.2 CH.sub.2                                                                    4 g  C.sub.2 H.sub.5                                                                          96 g 7.3 ×                                                                   10.sup.3                115    A-115 HOOCCH.sub.2        5 g  C.sub.3 H.sub.7                                                                          95 g 5.8 ×                                                                   10.sup.3                116    A-116                                                                                ##STR102##         5 g  CH.sub.2 C.sub.6 H.sub.5                                                                 95 g 7.5 ×                                                                   10.sup.3                117    A-117 HOOCCH.sub.2 CH.sub.2                                                                             5.5 g                                                                              C.sub.6 H.sub.5                                                                          94.5 g                                                                             6.5 ×                                                                   10.sup.3                118    A-118 HOOCCH.sub.2        4 g                                                                                 ##STR103##                                                                              96 g 5.3 ×                                                                   10.sup.3                119    A-119                                                                                ##STR104##         3 g                                                                                 ##STR105##                                                                              97 g 6.6 ×                                                                   10.sup.3                120    A-120 HO.sub.3 SCH.sub.2 CH.sub.2                                                                       3 g                                                                                 ##STR106##                                                                              97 g 8.8 ×                                                                   10.sup.3                121    A-121                                                                                ##STR107##         4 g                                                                                 ##STR108##                                                                              96 g 7.5 ×                                                                   10.sup.3                122    A-122                                                                                ##STR109##         7 g                                                                                 ##STR110##                                                                              93 g 5.5 ×                                                                   10.sup.3                123    A-123                                                                                ##STR111##         6 g                                                                                 ##STR112##                                                                              94 g 4.5 ×                                                                   10.sup.3                124    A-124                                                                                ##STR113##         4 g                                                                                 ##STR114##                                                                              96 g 5.6 ×             __________________________________________________________________________                                                          10.sup.3            

SYNTHESIS EXAMPLE 125 OF RESIN (A) Resin (A-125)

A mixed solution of 100 g of 1-naphthyl methacrylate, 150 g of tolueneand 50 g of isopropanol was heated to a temperature of 80° C. undernitrogen gas stream, and 5.0 g of 4,4'-azobis(4-cyanovaleric acid)(abbreviated as ACV) was added thereto, followed by reacting withstirring for 5 hours. Then, 1 g of ACV was added thereto, followed byreacting with stirring for 2 hours, and thereafter 1 g of ACV was addedthereto, followed by reacting with stirring for 3 hours. The resultingpolymer had a weight average molecular weight of 7.5×10³. ##STR115##

SYNTHESIS EXAMPLE 126 OF RESIN (A) Resin (A-126)

A mixed solution of 50 g of methyl methacrylate and 150 g of methylenechloride was cooled to -20° C. under nitrogen gas stream, and 1.0 g of a10% hexane solution of 1,1-diphenylhexyl lithium prepared just beforewas added thereto, followed by stirring for 5 hours. Carbon dioxide waspassed through the mixture at a flow rate of 10 ml/cc for 10 minuteswith stirring, the cooling was discontinued, and the reaction mixturewas allowed to stand to room temperature with stirring. Then, thereaction mixture was added to a solution of 50 ml of 1N hydrochloricacid in 1 liter of methanol to precipitate, and the white powder wascollected by filtration. The powder was washed with water until thewashings became neutral, and dried under reduced pressure to obtain 18 gof the polymer having a weight average molecular weight of 6.5×10³.##STR116##

SYNTHESIS EXAMPLE 127 OF RESIN (A) Resin (A-127)

A mixed solution of 97 g of benzyl methacrylate, 3 g of acrylic acid,9.7 g of Initiator (I-1) shown below and 100 g of tetrahydrofuran washeated to a temperature of 50° C. under nitrogen gas stream. ##STR117##

The solution was irradiated with light from a high-pressure mercury lampof 400 W at a distance of 10 cm through a glass filter for 12 hours toconduct a photopolymerization reaction. The reaction mixture obtainedwas reprecipitated in one liter of n-hexane, and the precipitates formedwere collected and dried to obtain 75 g of the polymer having a weightaverage molecular weight of 8×10³. ##STR118##

SYNTHESIS EXAMPLES 128 TO 133 OF RESIN (A) Resins (A-128) to (A-133)

Each of resins (A) shown in Table 5 below was synthesized in the sameprocedure as described in Synthesis Example 127 of Resin (A) except forusing 97 g of a monomer corresponding to the polymer component shown inTable 5 below and 0.044 moles of the initiator (I) shown in Table 5below in place of 97 g of benzyl methacrylate and 9.7 g of Initiator(I-1), respectively. The weight average molecular weight of each of thepolymers was in a range of from 7×10³ to 9×10³.

    TABLE 5      -      ##STR119##                                                                              S     ynthesis Example of Resin (A) Resin (A) Initiator (I) R.sup.30 R.sup.31     X      128 A-128      ##STR120##      ##STR121##      ##STR122##      ##STR123##     129 A-129      ##STR124##      ##STR125##      CH.sub.2 C.sub.6      H.sub.5     ##STR126##     130 A-130      ##STR127##      ##STR128##      ##STR129##      ##STR130##     131 A-131      ##STR131##      ##STR132##      C.sub.6      H.sub.5     ##STR133##     132 A-132      ##STR134##      ##STR135##      C.sub.2      H.sub.5     ##STR136##     133 A-133      ##STR137##      ##STR138##      CH.sub.2 C.sub.6      H.sub.5     ##STR139##

SYNTHESIS EXAMPLE 201 OF RESIN (A) Resin (A-201)

A mixed solution of 95 g of ethyl methacrylate, and 200 g oftetrahydrofuran was sufficiently degassed under nitrogen gas stream andcooled to -20° C. Then, 1.5 g of 1,1-diphenylbutyl lithium was added tothe mixture, and the reaction was conducted for 12 hours. Furthermore, amixed solution of 5 g of triphenylmethyl methacrylate and 5 g oftetrahydrofuran was sufficiently degassed under nitrogen gas stream,and, after adding the mixed solution to the above described mixture, thereaction was further conducted for 8 hours. The mixture was adjusted to0° C. and after adding thereto 10 ml of methanol, the reaction wasconducted for 30 minutes and the polymerization was terminated. Thetemperature of the polymer solution obtained was adjusted at 30° C.under stirring and, after adding thereto 3 ml of an ethanol solution of30% hydrogen chloride, the resulting mixture was stirred for one hour.Then, the solvent of the reaction mixture was distilled off underreduced pressure until the whole volume was reduced to a half, and thenthe mixture was reprecipitated from one liter of petroleum ether. Theprecipitates formed were collected and dried under reduced pressure toobtain 70 g of the polymer having a weight average molecular weight (Mw)of 8.5×10³. ##STR140## b: A bond connecting blocks (hereinafter thesame)

SYNTHESIS EXAMPLE 202 OF RESIN (A) Resin (A-202)

A mixed solution of 46 g of n-butyl methacrylate, 0.5 g of (tetraphenylprophynato) aluminum methyl, and 60 g of methylene chloride was raisedto a temperature of 30° C. under nitrogen gas stream. The mixture wasirradiated with light from a xenon lamp of 300 W at a distance of 25 cmthrough a glass filter, and the reaction was conducted for 12 hours. Tothe mixture was further added 4 g of benzyl methacrylate, afterlight-irradiating in the same manner as above for 8 hours, 3 g ofmethanol was added to the reaction mixture followed by stirring for 30minutes, and the reaction was terminated. Then, Pd--C was added to thereaction mixture, and a catalytic reduction reaction was conducted forone hour at 25° C. After removing insoluble substances from the reactionmixture by filtration, the reaction mixture was reprecipitated from 500ml of petroleum ether and the precipitates formed were collected anddried to obtain 33 g of the polymer having an Mw of 9.3×10³. ##STR141##

SYNTHESIS EXAMPLE 203 OF RESIN (A) Resin (A-203)

A mixed solution of 90 g of 2-chloro-6-methylphenyl methacrylate and 200g of toluene was sufficiently degassed under nitrogen gas stream andcooled to 0° C. Then, 2.5 g of 1,1-diphenyl-3-methylpentyl lithium wasadded to the mixture followed by stirring for 6 hours. Further, 25.4 gof 4-vinylbenzenecarboxylic acid triisopropylsilyl ester was added tothe mixture and, after stirring the mixture for 6 hours, 3 g of methanolwas added to the mixture followed by stirring for 30 minutes. Then, tothe reaction mixture was added 10 g of an ethanol solution of 30%hydrogen chloride and, after stirring the mixture at 25° C. for onehour, the mixture was reprecipitated from one liter of petroleum ether.The precipitates thus formed were collected, washed twice with 300 ml ofdiethyl ether and dried to obtain 58 g of the polymer having an Mw of7.8×10³. ##STR142##

SYNTHESIS EXAMPLE 204 OF RESIN (A) Resin (A-204)

A mixture of 95 g of phenyl methacrylate and 4.8 g of benzylN,N-diethyldithiocarbamate was placed in a vessel under nitrogen gasstream-followed by closing the vessel and heated to 60° C. The mixturewas irradiated with light from a high-pressure mercury lamp of 400 W ata distance of 10 cm through a glass filter for 10 hours to conductphotopolymerization. Then, 5 g of acrylic acid and 180 g of methyl ethylketone were added to the mixture and, after replacing the gas in thevessel with nitrogen, the mixture was light-irradiated again for 10hours. The reaction mixture was reprecipitated from 1.5 liters of hexaneand the precipitates formed were collected and dried to obtain 68 g ofthe polymer having an Mw of 9.5×10³. ##STR143##

SYNTHESIS EXAMPLES 205 TO 218 OF RESIN (A) Resins (A-205) to (A-218)

Each of resins (A) shown in Table 6 below was synthesized in the samemanner as described in Synthesis Example 201 of Resin (A) above. The Mwof each of the resins was in a range of from 6×10³ to 9.5×10³.

                                      TABLE 6                                     __________________________________________________________________________     ##STR144##                                                                   Synthesis Example of Resin (A)                                                                 Resin (A)                                                                           R.sub.0         Y                  x/y                 __________________________________________________________________________    205              A-205                                                                                ##STR145##                                                                                    ##STR146##        96/4                206              A-206                                                                                ##STR147##                                                                                    ##STR148##        96/4                207              A-207                                                                                ##STR149##                                                                                    ##STR150##        95/5                208              A-208                                                                                ##STR151##                                                                                    ##STR152##        92/8                209              A-209                                                                                ##STR153##                                                                                    ##STR154##        95/5                210              A-210                                                                                ##STR155##                                                                                    ##STR156##        97/3                211              A-211                                                                                ##STR157##                                                                                    ##STR158##         90/10              212              A-212                                                                                ##STR159##                                                                                    ##STR160##        98/2                213              A-213                                                                                ##STR161##                                                                                    ##STR162##        95/5                214              A-214                                                                                ##STR163##                                                                                    ##STR164##        94/6                215              A-215                                                                                ##STR165##                                                                                    ##STR166##        94/6                216              A-216                                                                                ##STR167##                                                                                    ##STR168##        95/5                217              A-217 C.sub.3 H.sub.7                                                                                ##STR169##        95/5                218              A-218 CH.sub.2 C.sub.6 H.sub.5                                                                       ##STR170##        96/4                __________________________________________________________________________

SYNTHESIS EXAMPLES 219 TO 223 OF RESIN (A) Resins (A-219) to (A-223)

Each of the resins (A) shown in Table 7 below was synthesized in thesame manner as described in synthesis Example 204 of Resin (A) above.The Mw of each of the resins was in a range of from 8×10³ to 1×10⁴.

                                      TABLE 7                                     __________________________________________________________________________     ##STR171##                                                                   Synthesis Example                                                                       Resin                                         x/y/z                 of Resin (A)                                                                            (A) R.sub.0     X           Y                 (weight               __________________________________________________________________________                                                            ratio)                219       A-219                                                                             CH.sub.3                                                                                   ##STR172##                                                                                ##STR173##       65/30/5               220       A-220                                                                             C.sub.2 H.sub.5                                                                            ##STR174##                                                                                ##STR175##       72/25/3               221       A-221                                                                              ##STR176##                                                                                ##STR177##                                                                                ##STR178##       81/15/4               222       A-222                                                                              ##STR179##                                                                                ##STR180##                                                                                ##STR181##       75/20/5               223       A-223                                                                              ##STR182##                                                                                ##STR183##                                                                                ##STR184##       75/20/5               __________________________________________________________________________

Synthesis examples of the resin (B) are specifically illustrated below.

SYNTHESIS EXAMPLE 1 OF RESIN (B) Resin (B-1)

A mixed solution of 67 g of methyl methacrylate, 32 g of methylacrylate, 1 g of acrylic acid, 17.5 g of Initiator (I-1) having thefollowing structure and 150 g of tetrahydrofuran was heated to atemperature of 50° C. under nitrogen gas stream. The solution wasirradiated with light from a high-pressure mercury lamp of 400 W at adistance of 10 cm through a glass filter for 10 hours to conductphotopolymerization. The reaction mixture obtained was reprecipitated inone liter of methanol, and the precipitates formed were collected anddried to obtain 72 g of the polymer having a weight avarage molecularweight (Mw) of 5×10⁴. ##STR185##

SYNTHESIS EXAMPLE 2 OF RESIN (B) Resin (B-2)

Resin (B-2) was synthesized under the same condition as described inSynthesis Example 1 of Resin (B) except for using 10 g of Initiator(I-2) having the following structure in place of 17.5 g of Initiator(I-1). The yield of the resulting polymer was 75 g and the Mw thereofwas 6×10⁴. ##STR186##

SYNTHESIS EXAMPLES 3 TO 9 OF RESIN (B) Resins (B-3) to (B-9)

Each of polymers shown in Table 8 below was synthesized under the samecondition as described in Synthesis Example 1 of Resin (B) except forusing a mixed solution of 65 g of methyl methacrylate, 30 g of methylacrylate, 4 g of N-vinylpyrrolidone, 1 g of methacrylic acid, 0.0312moles of each of Initiators shown in Table 8 below and 100 g oftetrahydrofuran. The Mw of each of the resulting polymers was in a rangeof from 6×10⁴ to 8×10⁴.

                                      TABLE 8                                     __________________________________________________________________________     ##STR187##                                                                    ##STR188##                                                                    ##STR189##                                                                         ##STR190##                                                                                               ##STR191##                                                                                ##STR192##                       __________________________________________________________________________          ##STR193##             (I-3)                                                                             ##STR194##                                                                                ##STR195##                       4                                                                                   ##STR196##             (I-4)                                                                             ##STR197##                                                                                ##STR198##                       5                                                                                   ##STR199##             (I-5)                                                                             ##STR200##                                                                                ##STR201##                       6                                                                                   ##STR202##             (I-6)                                                                             ##STR203##                                                                                ##STR204##                       7                                                                                   ##STR205##             (I-7)                                                                            CH.sub.2 C.sub.6 H.sub.5                                                                   ##STR206##                       8                                                                                   ##STR207##             (I-8)                                                                             ##STR208##                                                                                ##STR209##                       9                                                                                   ##STR210##             (I-9)                                                                             ##STR211##                                                                                ##STR212##                       __________________________________________________________________________

SYNTHESIS EXAMPLES 10 TO 15 OF RESIN (B) Resins (B-10) to (B-15)

Each of the polymers shown in Table 9 below was synthesized under thesame condition as described in Synthesis Example 1 of Resin (B) exceptfor using each of monomers corresponding to the polymer components shownin Table 9 below in place of methyl methacrylate, methyl acrylate andacrylic acid. The Mw of each of the resulting polymers was in a range offrom 5×10⁴ to 6×10⁴.

                                      TABLE 9                                     __________________________________________________________________________     ##STR213##                                                                   Synthesis Example                                                             of Resin (B)                                                                            Resin (B)                                                                           ##STR214##                                                    __________________________________________________________________________    10        (B-10)                                                                              ##STR215##                                                    11        (B-11)                                                                              ##STR216##                                                    12        (B-12)                                                                              ##STR217##                                                    13        (B-13)                                                                              ##STR218##                                                    14        (B-14)                                                                              ##STR219##                                                    15        (B-15)                                                                              ##STR220##                                                    __________________________________________________________________________

SYNTHESIS EXAMPLES 16 TO 19 OF RESIN (B) Resins (B-16) to (B-19)

Each of the polymers shown in Table 10 below was synthesized under thesame condition as described in Synthesis Example 1 of Resin (B) exceptfor using a mixed solution of 71.5 g of of methyl methacrylate, 25 g ofmethyl acrylate, 2.5 g of acrylonitrile, 1 g of acrylic acid, 0.0315moles of Initiator shown in Table 10 below and 100 g of tetrahydrofuran.The Mw of each of the resulting polymers was in a range of from 5×10⁴ to8×10⁴.

    TABLE 10      -      ##STR221##      ##STR222##      ##STR223##      ##STR224##      ##STR225##      ##STR226##      ##STR227##      16 (B-16)      ##STR228##      (I-10)      ##STR229##      ##STR230##     17 (B-17)      ##STR231##      (I-11)      ##STR232##      ##STR233##     18 (B-18)      ##STR234##      (I-12)      ##STR235##      ##STR236##     19 (B-19)      ##STR237##      (I-13)      ##STR238##      ##STR239##

SYNTHESIS EXAMPLES 20 TO 24 OF RESIN (B) Resins (B-20) to (B-24)

A mixture of 11.3 g of Initiator (I-2) described above and monomerscorresponding to the polymer components shown in Table 11 below washeated to a temperature of 40° C. under nitrogen gas stream, followed bylight irradiation for polymerization in the same manner as described inSynthesis Example 1 of Resin (B). The solid material obtained wascollected, dissolved in 250 ml of tetrahydrofuran, reprecipitated in 1.5liters of methanol, and the precipitates formed were collected byfiltration and dried. The yield of each of the resulting polymers was ina range of from 60 to 75 g and the Mw thereof was in a range of from6×10⁴ to 8×10⁴.

                                      TABLE 11                                    __________________________________________________________________________     ##STR240##                                                                   Synthesis Example                                                             of Resin (B)                                                                            Resin (B)                                                                           ##STR241##                                                    __________________________________________________________________________    20        (B-20)                                                                              ##STR242##                                                    21        (B-21)                                                                              ##STR243##                                                    22        (B-22)                                                                              ##STR244##                                                    23        (B-23)                                                                              ##STR245##                                                    24        (B-24)                                                                              ##STR246##                                                    __________________________________________________________________________

SYNTHESIS EXAMPLE 101 OF RESIN (B) Resin (B-101)

A mixture of 74 g of methyl methacrylate and 12.4 g of Initiator (I-1)having the following structure was heated to a temperature of 50° C.under nitrogen gas stream.

The solution was irradiated with light from a high-pressure mercury lampof 400 W at a distance of 10 cm through a glass filter for 5 hours toconduct photopolymerization. ##STR247##

The resulting polymer was dissolved by adding 100 g of tetrahydrofuran,then 25 g of methyl acrylate and 1.0 g of acrylic acid were addedthereto, and the mixture was again heated to a temperature of 50° C.under nitrogen gas stream. The mixture was irradiated with light in thesame manner as above for 10 hours, the reaction mixture obtained wasreprecipitated in 2 liters of methanol, and the precipitates formed werecollected and dried. The yield of the resulting polymer was 78 g and theweight average molecular weight (Mw) thereof was 6×10⁴. ##STR248##wherein --b-- represents a bond between blocks (hereinafter the same).

SYNTHESIS EXAMPLE 102 OF RESIN (B) Resin (B-102)

Resin (B-102) was synthesized under the same condition as described inSynthesis Example 101 of Resin (B) except for using 16.0 g of Initiator(I-2) having the following structure in place of 12.4 g of Initiator(I-1). The yield of the resulting polymer was 72 g and the Mw thereofwas 6×10⁴. ##STR249##

SYNTHESIS EXAMPLES 103 TO 109 OF RESIN (B) Resins (B-103) to (B-109)

A mixture of 65 g of methyl methacrylate and 0.013 moles of each ofInitiators shown in Table 12 below was subjected to aphotopolymerization reaction in the same manner as described inSynthesis Example 101 of Resin (B). The resulting polymer was dissolvedby adding 100 g of tetrahydrofuran, then 30 g of methyl acrylate, 4 g ofN-vinylpyrrolidone and 1 g of methacrylic acid were added thereto, andthe mixture was subjected to photopolymerization and reprecipitation inthe same manner as described in Synthesis Example 101 of Resin (B). TheMw of each of the resulting polymers was in a range of from 5×10⁴ to8×10⁴.

                                      TABLE 12                                    __________________________________________________________________________     ##STR250##                                                                    ##STR251##                                                                    ##STR252##                                                                            ##STR253##                                                                                            ##STR254##                                                                                ##STR255##                       __________________________________________________________________________    103                                                                                    ##STR256##                                                                                            ##STR257##                                                                                ##STR258##                       104                                                                                    ##STR259##                                                                                            ##STR260##                                                                                ##STR261##                       105                                                                                    ##STR262##                                                                                            ##STR263##                                                                                ##STR264##                       106                                                                                    ##STR265##                                                                                            ##STR266##                                                                                ##STR267##                       107                                                                                    ##STR268##             CH.sub.2 C.sub.6 H.sub.5                                                                   ##STR269##                       108                                                                                    ##STR270##                                                                                            ##STR271##                                                                                ##STR272##                       109                                                                                    ##STR273##                                                                                            ##STR274##                                                                                ##STR275##                       __________________________________________________________________________

SYNTHESIS EXAMPLES 110 TO 115 OF RESIN (B) Resins (B-110) to (B-115)

Each of the polymers shown in Table 13 below was synthesized under thesame condition as described in Synthesis Example 101 of Resin (B) exceptfor using each of monomers corresponding to the polymer components shownin Table 13 below in place of methyl methacrylate, methyl acrylate andacrylic acid. The Mw of each of the resulting polymers was in a range offrom 5×10⁴ to 6×10⁴.

                                      TABLE 13                                    __________________________________________________________________________     ##STR276##                                                                   Synthesis Example                                                             of Resin (B)                                                                            Resin (B)                                                                           ##STR277##                                                    __________________________________________________________________________    110       (B-110)                                                                             ##STR278##                                                    111       (B-111)                                                                             ##STR279##                                                    112       (B-112)                                                                             ##STR280##                                                    113       (B-113)                                                                             ##STR281##                                                    114       (B-114)                                                                             ##STR282##                                                    115       (B-115)                                                                             ##STR283##                                                    __________________________________________________________________________

SYNTHESIS EXAMPLES 116 TO 121 OF RESIN (B) Resins (B-116) to (B-121)

A mixed solution of 16.5 g of methyl acrylate, 2.5 g of acrylonitrile,1.0 g of acrylic acid, 0.0072 moles of Initiator shown in Table 14 belowand 20 g of tetrahydrofuran was subjected to light irradiation for 15hours in the same manner as described in Synthesis Example 101 of Resin(B). To the reaction mixture were added 60 g of methyl methacrylate, 20g of methyl acrylate and 80 g of tetrahydrofuran, followed bypolymerization reaction and reprecipitation in the same manner asdescribed in Synthesis Example 101 of Resin (B). The Mw of each of theresulting polymers was in a range of from 5×10⁴ to 8×10⁴.

    TABLE 14      -      ##STR284##      ##STR285##      ##STR286##      ##STR287##      ##STR288##      ##STR289##      ##STR290##      116 (B-116)      ##STR291##      ##STR292##      ##STR293##     117 (B-117)      ##STR294##      ##STR295##      ##STR296##     118 (B-118)      ##STR297##      ##STR298##      ##STR299##     119 (B-119)      ##STR300##      ##STR301##      ##STR302##     120 (B-120)      ##STR303##      ##STR304##      ##STR305##     121 (B-121)      ##STR306##      ##STR307##      ##STR308##

SYNTHESIS EXAMPLES 122 TO 126 OF RESIN (B) Resins (B-122) to (B-126)

A mixture of monomers corresponding to the polymer components shown inTable 15 below and 14 g of Initiator (I-2) described above was heated toa temperature of 40° C. under nitrogen gas stream, followed by lightirradiation in the same manner as described in Synthesis Example 101 ofResin (B) to conduct polymerization for 5 hours. The solid materialobtained was collected, dissolved in 100 g of tetrahydrofuran, and then25 g of methyl acrylate and 1.5 g of acrylic acid were added thereto.The mixture was heated to a temperature of 50° C. under nitrogen gasstream and polymerized by irradiation with light in the same manner asabove. The reaction mixture obtained was reprecipitated in one liter ofmethanol, and the precipitates formed were collected and dried. Theyield of each of the resulting polymers was in a range of from 65 to 75g and the Mw thereof was in a range of from 5×10.sup. 4 to 7×10⁴.

                                      TABLE 15                                    __________________________________________________________________________     ##STR309##                                                                    ##STR310##                                                                   Synthesis Example                                                             of Resin (B)                                                                            Resin (B)                                                                          Polymer Component of Block                                                     ##STR311##                                                    __________________________________________________________________________    122       (B-122)                                                                             ##STR312##                                                    123       (B-123)                                                                             ##STR313##                                                    124       (B-124)                                                                             ##STR314##                                                    125       (B-125)                                                                             ##STR315##                                                    126       (B-126)                                                                             ##STR316##                                                    __________________________________________________________________________

SYNTHESIS EXAMPLES 127 TO 133 OF RESIN (B) Resins (B-127) to (B-133)

A mixed solution of 56 g of methyl methacrylate, 24 g of methyl acrylateand 10 g of Initiator (I-3) having the following structure was heated toa temperature of 40° C. under nitrogen gas stream, followed by lightirradiation in the same manner as described in Synthesis Example 101 ofResin (B) to conduct polymerization for 4 hours. The solid materialobtained was dissolved in 100 g of tetrahydrofuran, and monomerscorresponding to the polymer components shown in Table 16 below wereadded thereto. The mixture was heated to a temperature of 50° C. undernitrogen gas stream and polymerized by irradiation with light in thesame manner as above. The reaction mixture obtained was reprecipitatedin one liter of methanol, and the precipitates formed were collected anddried. The yield of each of the resulting polymers was in a range offrom 65 to 75 g and the Mw thereof was in a range of from 4×10⁴ to7×10⁴. ##STR317##

                                      TABLE 16                                    __________________________________________________________________________     ##STR318##                                                                   Synthesis Example                                                             of Resin (B)                                                                            Resin (B)                                                                           ##STR319##                                                    __________________________________________________________________________    127       (B-127)                                                                             ##STR320##                                                    128       (B-128)                                                                             ##STR321##                                                    129       (B-129)                                                                             ##STR322##                                                    130       (B-130)                                                                             ##STR323##                                                    131       (B-131)                                                                             ##STR324##                                                    132       (B-132)                                                                             ##STR325##                                                    133       (B-133)                                                                             ##STR326##                                                    __________________________________________________________________________

SYNTHESIS EXAMPLE 201 OF RESIN (B) Resin (B-201)

A mixture of 74 g of methyl methacrylate and 12.4 g of Initiator (I-201)having the following structure was heated to a temperature of 50° C.under nitrogen gas stream. The solution was irradiated with light from ahigh-pressure mercury lamp of 400 W at a distance of 10 cm through aglass filter for 5 hours to conduct photopolymerization. ##STR327##

The resulting polymer was dissolved by adding 100 g of tetrahydrofuran,then 25 g of methyl acrylate and 1.0 g of acrylic acid were addedthereto, and the mixture was again heated to a temperature of 50° C.under nitrogen gas stream. The mixture was irradiated with light in thesame manner as above for 10 hours, the reaction mixture obtained wasreprecipitated in 2 liters of methanol, and the precipitates formed werecollected and dried. The yield of the resulting polymer was 78 g and theweight average molecular weight (Mw) thereof was 6×10⁴. ##STR328##wherein --b-- represents a bond between blocks (hereinafter the same).

SYNTHESIS EXAMPLE 202 OF RESIN (B) Resin (B-202)

A mixture of 50.3 g of methyl methacrylate, 24.7 g of methyl acrylate,8.0 g of Initiator (I-202) having the following structure and 75 g oftetrahydrofuran was heated to a temperature of 50° C. under nitrogen gasstream. The solution was irradiated with light for 6 hours under thesame condition as described in Synthesis Example 201 of Resin (B).##STR329##

To the resulting polymer was added a mixed solution of 23 g of methylmethacrylate, 2.0 g of acrylonitrile and 25 g of tetrahydrofuran, andthe mixture was again heated to a temperature of 60° C. under nitrogengas stream and irradiated with light for 12 hours in the same manner asabove to conduct photopolymerization. The reaction mixture obtained wasreprecipitated in 1.5 liters of methanol, and the precipitates formedwere collected and dried. The yield of the resulting polymer was 75 gand the Mw thereof was 1.2×10⁵. ##STR330##

SYNTHESIS EXAMPLES 203 TO 210 OF RESIN (B) Resins (B-203) to (B-210)

A mixture of 65 g of methyl methacrylate and 0.008 moles of each ofInitiators shown in Table 17 below was subjected to aphotopolymerization reaction in the same manner as described inSynthesis Example 201 of Resin (B). The resulting polymer was dissolvedby adding 100 g of tetrahydrofuran, then 32.2 g of methyl acrylate, 2.0g of N-vinylpyrrolidone and 0.8 g of methacrylic acid were addedthereto, and the mixture was subjected to photopolymerization andreprecipitation in the same manner as described in Synthesis Example 201of Resin (B). The Mw of each of the resulting polymers was in a range offrom 8×10⁴ to 1.0×10⁵.

    TABLE 17      -      ##STR331##      ##STR332##      ##STR333##      ##STR334##      ##STR335##      ##STR336##      203      ##STR337##      (1-203)      ##STR338##      ##STR339##     204      ##STR340##      (1-204)      ##STR341##      ##STR342##     205      ##STR343##      (1-205)      ##STR344##      ##STR345##     206      ##STR346##      (1-206)      ##STR347##      ##STR348##     207      ##STR349##      (1-207) (CH.sub.2).sub.6      COOH     ##STR350##     208      ##STR351##      (1-208) (CH.sub.2).sub.2      COOH     ##STR352##     209      ##STR353##      (1-209) (CH.sub.2).sub.4      COOH     ##STR354##     210      ##STR355##      (1-210)      ##STR356##      ##STR357##

SYNTHESIS EXAMPLES 211 TO 216 OF RESIN (B) Resins (B-211) to (B-216)

Each of polymers shown in Table 18 below was synthesized under the samecondition as described in Synthesis Example 201 of Resin (B) except forusing each of monomers corresponding to the polymer components shown inTable 18 below in place of methyl methacrylate, methyl acrylate andacrylic acid. The Mw of each of the resulting polymers was in a range offrom 5×10⁴ to 6×10⁴.

                                      TABLE 18                                    __________________________________________________________________________     ##STR358##                                                                   Synthesis Example                                                             of Resin (B)                                                                            Resin (B)                                                                          [P]](weight ratio)                                             __________________________________________________________________________    211       (B-211)                                                                             ##STR359##                                                    212       (B-212)                                                                             ##STR360##                                                    213       (B-213)                                                                             ##STR361##                                                    214       (B-214)                                                                             ##STR362##                                                    215       (B-215)                                                                             ##STR363##                                                    216       (B-216)                                                                             ##STR364##                                                    __________________________________________________________________________

SYNTHESIS EXAMPLES 217 TO 223 OF RESIN (B) Resins (B-217) to (B-223)

A mixed solution of 63.6 g of methyl methacrylate, 31.4 g of methylacrylate, 5 g of 2-hydroxyethyl methacrylate, 1×10⁻³ mole of Initiatorshown in Table 19 below and 100 g of tetrahydrofuran was subjected tolight irradiation for 8 hours in the same manner as described inSynthesis Example 201 of Resin (B). The resulting polymer wasreprecipitated in 1.5 liters of methanol and the precipitates formedwere collected by filtration and dried. The yield of each of thepolymers obtained was in a range of from 70 to 80 g and the Mw thereofwas in a range of from 8×10⁴ to 10×10⁴.

    TABLE 19      -      ##STR365##      ##STR366##      ##STR367##      ##STR368##      ##STR369##      ##STR370##      ##STR371##      217 (B-217)      ##STR372##      (I-211)      ##STR373##      ##STR374##     218 (B-218)      ##STR375##      (I-212)      ##STR376##      ##STR377##     219 (B-219)      ##STR378##      (I-213)      ##STR379##      ##STR380##     220 (B-220)      ##STR381##      (I-214)      ##STR382##      ##STR383##     221 (B-221)      ##STR384##      (I-215)      ##STR385##      ##STR386##     222 (B-222)      ##STR387##      (I-216)      ##STR388##      ##STR389##     223 (B-223)      ##STR390##      (I-217)      ##STR391##      ##STR392##

SYNTHESIS EXAMPLES 224 TO 228 OF RESIN (B) Resins (B-224) to (B-228)

A mixture of monomers corresponding to the polymer components shown inTable 20 below and 15.4 g of Initiator (I-202) described above washeated to a temperature of 40° C. under nitrogen gas stream, followed bylight irradiation in the same manner as described in Synthesis Example201 of Resin (B) to conduct polymerization for 5 hours. The solidmaterial obtained was collected, dissolved in 100 g of tetrahydrofuran,and then 19.5 g of methyl acrylate and 0.5 g of acrylic acid were addedthereto. The mixture was heated to a temperature of 50° C. undernitrogen gas stream and polymerized by irradiation with light in thesame manner as above. The reaction mixture obtained was reprecipitatedin one liter of methanol, and the precipitates formed were collected anddried. The yield of each of the resulting polymers was in a range offrom 65 to 75 g and the Mw thereof was in a range of from 9×10⁴ to1.2×10⁵.

                  TABLE 20                                                        ______________________________________                                         ##STR393##                                                                    ##STR394##                                                                    ##STR395##                                                                   Synthesis Example   Polymer Component of                                      of Resin (B)                                                                             Resin (B)                                                                               ##STR396##                                               ______________________________________                                        224        (B-224)                                                                                 ##STR397##                                               225        (B-225)                                                                                 ##STR398##                                               226        (B-226)                                                                                 ##STR399##                                               227        (B-227)                                                                                 ##STR400##                                               228        (B-228)                                                                                 ##STR401##                                               ______________________________________                                    

SYNTHESIS EXAMPLES 229 TO 235 OF RESIN (B) Resins (B-229) to (B-235)

A mixture of 57 g of methyl methacrylate, 28 g of methyl acrylate and1.3 g of Initiator (I-218) having the following structure was heated toa temperature of 40° C. under nitrogen gas stream, followed by lightirradiation in the same manner as described in Synthesis Example 201 ofResin (B) to conduct polymerization for 4 hours. ##STR402##

The solid material obtained was dissolved in 100 g of tetrahydrofuran,and monomers corresponding to the polymer components shown in Table 21below were added thereto. The mixture was heated to a temperature of 50°C. under nitrogen gas stream and polymerized by irradiation with lightin the same manner as above. The reaction mixture obtained wasreprecipitated in one liter of methanol, and the precipitates formedwere collected and dried. The yield of each of the resulting polymerswas in a range of from 70 to 80 g and the Mw thereof was in a range offrom 9×10⁴ to 1.1×10⁵.

                                      TABLE 21                                    __________________________________________________________________________     ##STR403##                                                                    ##STR404##                                                                   Synthesis Example                                                             of Resin (B)                                                                            Resin (B)                                                                           ##STR405##                                                    __________________________________________________________________________    229       (B-229)                                                                             ##STR406##                                                    230       (B-230)                                                                             ##STR407##                                                    231       (B-231)                                                                             ##STR408##                                                    232       (B-232)                                                                             ##STR409##                                                    233       (B-233)                                                                             ##STR410##                                                    234       (B-234)                                                                             ##STR411##                                                    235       (B-235)                                                                             ##STR412##                                                    __________________________________________________________________________

EXAMPLE I-1

A mixture of 6 g (solid basis) of Resin (A-1), 34 g (solid basis) ofResin (B-1), 200 g of photoconductive zinc oxide, 0.018 g of Cyanine Dye(I-I) shown below, 0.15 g of phthalic anhydride and 300 g of toluene wasdispersed by a homogenizer (manufactured by Nippon Seiki K.K.) at arotation of 6×10³ r.p.m. for 10 minutes to prepare a coating compositionfor a light-sensitive layer. The coating composition was coated onpaper, which had been subjected to electrically conductive treatment, bya wire bar at a dry coverage of 18 g/m², followed by drying at 110° C.for 10 seconds. The coated material was then allowed to stand in a darkplace at 20° C. and 65% RH for 24 hours to prepare anelectrophotographic light-sensitive material. ##STR413##

COMPARATIVE EXAMPLE I-1

An electrophotographic light-sensitive material was prepared in the samemanner as in Example I-1, except for using 34 g of Resin (R-I-1) shownbelow in place of 34 g of Resin (B-1) used in Example I-1. ##STR414##

COMPARATIVE EXAMPLE I-2

An electrophotographic light-sensitive material was prepared in the samemanner as in Example I-1, except for using 34 g of Resin (R-I-2) shownbelow in place of 34 g of Resin (B-1) used in Example I-1. ##STR415##

With each of the light-sensitive materials thus prepared, electrostaticcharacteristics and image forming performance were evaluated. Theresults obtained are shown in Table I-1 below.

                  TABLE I-1                                                       ______________________________________                                                  Example                                                                              Comparative Comparative                                                I-1    Example I-1 Example I-2                                      ______________________________________                                        Electrostatic                                                                 Characteristics*.sup.1)                                                       V.sub.10 (-V)                                                                 I (20° C., 65% RH)                                                                 580      570         575                                          II (30° C., 80% RH)                                                                570      560         560                                          D.R.R. (90 sec                                                                value) (%)                                                                    I (20° C., 65% RH)                                                                 84       80          82                                           II (30° C., 80% RH)                                                                82       75          78                                           E.sub.1/10 (erg/cm.sup.2)                                                     I (20° C., 65% RH)                                                                 25       38          33                                           II (30° C., 80% RH)                                                                27       41          38                                           E.sub.1/100 (erg/cm.sup.2)                                                    I (20° C., 65% RH)                                                                 39       61          52                                           II (30° C., 80% RH)                                                                41       66          59                                           Image Forming                                                                 Performance*.sup.2)                                                           I (20° C., 65% RH)                                                                 Very     Scratches of                                                                              Scratches of                                             good     fine lines and                                                                            fine lines and                                                    letters,    letters,                                                          unevenness in                                                                             unevenness in                                                     half tone area                                                                            half tone area                               II (30° C., 80% RH)                                                                Very     Scratches of                                                                              Scratches of                                             good     fine lines and                                                                            fine lines and                                                    letters,    letters,                                                          unevenness in                                                                             unevenness in                                                     half tone area                                                                            half tone area                               ______________________________________                                    

The evaluation of each item shown in Table I-1 was conducted in thefollowing manner.

*1) Electrostatic Characteristics

The light-sensitive material was charged with a corona discharge to avoltage of -6 kV for 20 seconds in a dark room using a paper analyzer("Paper Analyzer SP-428" manufactured by Kawaguchi Denki K.K.). Tenseconds after the corona discharge, the surface potential V₁₀ wasmeasured. The sample was then allowed to stand in the dark for anadditional 90 seconds, and the potential V₁₀₀ was measured. The darkdecay retention rate (DRR; %), i.e., percent retention of potentialafter dark decay for 90 seconds, was calculated from the followingequation:

    DRR(%)=(V.sub.100 /V.sub.10)×100

Separately, the surface of photoconductive layer was charged to -400 Vwith a corona discharge and then exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm), and the time required for decay of the surface potential V₁₀ toone-tenth was measured, and the exposure amount E_(1/10) (erg/cm²) wascalculated therefrom. Further, in the same manner as described above thetime required for decay of the surface potential V₁₀ to one-hundredthwas measured, and the exposure amount E_(1/100) (erg/cm²) was calculatedtherefrom. The measurements were conducted under ambient condition of20° C. and 65% RH (I) or 30° C. and 80% RH (II).

*2) Image Forming Performance

After the light-sensitive material was allowed to stand for one dayunder the ambient condition shown below, the light-sensitive materialwas charged to -6 kV and exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm; output: 2.8 mW) at an exposure amount of 64 erg/cm² (on thesurface of the photoconductive layer) at a pitch of 25 μm and a scanningspeed of 300 m/sec. The thus formed electrostatic latent image wasdeveloped with a liquid developer ("ELP-T" produced by Fuji Photo FilmCo., Ltd.), washed with a rinse solution of isoparaffinic solvent("Isopar G" manufactured by Esso Chemical K.K.) and fixed. Theduplicated image obtained was visually evaluated for fog and imagequality. The ambient condition at the time of image formation was 20° C.and 65% RH (I) or 30° C. and 80% RH (II).

As can be seen from the results shown in Table I-1, the light-sensitivematerial according to the present invention had good electrostaticcharacteristics. The duplicated image obtained thereon was clear andfree from background fog. On the contrary, with the light-sensitivematerials of Comparative Examples I-1 and I-2 the decrease inphotosensitivity (E_(1/10) and E_(1/100)) occurred, and in theduplicated images the scratches of fine lines and letters were observedand a slight background fog remained without removing after the rinsetreatment. Further, the occurrence of unevenness in half tone areas ofcontinuous gradation of the original was observed regardless of theelectrostatic characteristics.

The value of E_(1/100) is largely different between the light-sensitivematerial of the present invention and those of the comparative examples.The value of E_(1/100) indicates an electrical potential remaining inthe non-image areas after exposure at the practice of image formation.The smaller this value, the less the background fog in the non-imageareas.

More specifically, it is required that the remaining potential isdecreased to -10 V or less. Therefore, an amount of exposure necessaryto make the remaining potential below -10 V is an important factor. Inthe scanning exposure system using a semiconductor laser beam, it isquite important to make the remaining potential below -10 V by a smallexposure amount in view of a design for an optical system of aduplicator (such as cost of the device, and accuracy of the opticalsystem).

From all these considerations, it is thus clear that anelectrophotographic light-sensitive material satisfying both therequirements of electrostatic characteristics and image formingperformance and being advantageously employed particularly in a scanningexposure system using a semiconductor laser beam can be obtained onlywhen the binder resin according to the present invention is used.

EXAMPLE I-2

A mixture of 5 g (solid basis) of Resin (A-3), 35 g (solid basis) ofResin (B-2), 200 g of photoconductive zinc oxide, 0.020 g of Methine Dye(I-II) shown below, 0.20 g of N-hydroxymaleinimide and 300 g of toluenewas treated in the same manner as described in Example I-1 to prepare anelectrophotographic light-sensitive material. ##STR416##

With the light-sensitive material thus-prepared, a film property interms of surface smoothness, electrostatic characteristics and imageforming performance were evaluated. Further, printing property wasevaluated when it was used as an electrophotographic lithographicprinting plate precursor. The results obtained are shown in Table I-2below.

                  TABLE I-2                                                       ______________________________________                                                              Example I-2                                             ______________________________________                                        Smoothness of Photoconductive Layer*.sup.3)                                                           650                                                   (sec/cc)                                                                      Electrostatic Characteristics                                                 V.sub.10 (-V)                                                                 I (20° C., 65% RH)                                                                             680                                                   II (30° C., 80% RH)                                                                            665                                                   D.R.R.                                                                        (90 sec value) (%)                                                            I (20° C., 65% RH)                                                                             88                                                    II (30° C., 80% RH)                                                                            85                                                    E.sub.1/10 (erg/cm.sup.2)                                                     I (20° C., 65% RH)                                                                             16                                                    II (30° C., 80% RH)                                                                            17                                                    E.sub.1/100 (erg/cm.sup.2)                                                    I (20° C., 65% RH)                                                                             22                                                    II (30° C., 80% RH)                                                                            26                                                    Image Forming Performance                                                     I (20° C., 65% RH)                                                                             Very good                                             II (30° C., 80% RH)                                                                            Very good                                             Contact Angle with Water*.sup.4) (°)                                                           10 or less                                            Printing Durability*.sup.5)                                                                           10,000 prints                                         ______________________________________                                    

The evaluation of each item shown in Table I-2 was conducted in thefollowing manner.

*3) Smoothness of Photoconductive Layer

The smoothness (sec/cc) of the light-sensitive material was measuredusing a Beck's smoothness test machine (manufactured by Kumagaya RikoK.K.) under an air volume condition of 1 cc.

*4) Contact Angle with Water

The light-sensitive material was passed once through an etchingprocessor using a solution prepared by diluting an oil-desensitizingsolution ("ELP-EX" produced by Fuji Photo Film Co., Ltd.) to a two-foldvolume with distilled water to conduct oil-desensitization treatment onthe surface of the photoconductive layer. On the thus oil-desensitizedsurface was placed a drop of 2 μl of distilled water, and the contactangle formed between the surface and water was measured using agoniometer.

*5) Printing Durability

The light-sensitive material was subjected to plate making in the samemanner as described in *2) above to form toner images, and the surfaceof the photoconductive layer was subjected to oil-desensitizationtreatment under the same condition as in *4) above. The resultinglithographic printing plate was mounted on an offset printing machine("Oliver Model 52", manufactured by Sakurai Seisakusho K.K.), andprinting was carried out on paper. The number of prints obtained untilbackground stains in the non-image areas appeared or the quality of theimage areas was deteriorated was taken as the printing durability. Thelarger the number of the prints, the higher the printing durability.

As can be seen from the results shown in Table I-2, the light-sensitivematerial according to the present invention had good surface smoothness,film strength and electrostatic characteristics of the photoconductivelayer. The duplicated image obtained was clear and free from backgroundfog in the non-image area. These results appear to be due to sufficientadsorption of the binder resin onto the photoconductive substance andsufficient covering of the surface of the particles with the binderresin. For the same reason, when it was used as an offset master plateprecursor, oil-desensitization of the offset master plate precursor withan oil-desensitizing solution was sufficient to render the non-imageareas satisfactorily hydrophilic, as shown by a small contact angle of10° or less with water. On practical printing using the resulting masterplate, 10,000 prints of clear image without background stains wereobtained.

From these results it is believed that the resin (A) and the resin (B)according to the present invention suitably interacts with zinc oxideparticles to form the condition under which an oil-desensitizingreaction proceeds easily and sufficiently with an oil-desensitizingsolution and that the remarkable improvement in film strength isachieved by the action of the resin (B).

EXAMPLES I-3 TO I-18

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example I-2, except for using each of Resins(A) and Resins (B) shown in Table I-3 below in place of Resin (A-3) andResin (B-2) used in Example I-2, respectively.

The electrostatic characteristics of the resulting light-sensitivematerials were evaluated in the same manner as described in Example I-2.The results obtained are shown in Table I-3 below.

                  TABLE I-3                                                       ______________________________________                                                                                   E.sub.1/100                               Resin   Resin   V.sub.10                                                                            D.R.R.                                                                              E.sub.1/10                                                                            (erg/                              Example                                                                              (A)     (B)     (-V)  (%)   (erg/cm.sup.2)                                                                        cm.sup.2)                          ______________________________________                                        I-3    A-2     B-2     575   82    26      42                                 I-4    A-4     B-3     580   82    27      41                                 I-5    A-5     B-6     570   80    28      43                                 I-6    A-6     B-9     560   78    20      32                                 I-7    A-7     B-10    670   84    18      29                                 I-8    A-8     B-11    660   84    20      30                                 I-9    A-9     B-12    560   80    28      43                                 I-10   A-10    B-13    660   83    17      28                                 I-11   A-12    B-14    580   81    22      31                                 I-12   A-13    B-15    585   81    23      30                                 I-13   A-17    B-18    610   82    19      30                                 I-14   A-18    B-19    620   81    20      31                                 I-15   A-23    B-20    665   83    19      28                                 I-16   A-24    B-21    570   79    26      36                                 I-17   A-28    B-22    565   78    28      42                                 I-18   A-29    B-23    670   82    19      30                                 ______________________________________                                    

The electrostatic characteristics were evaluated under condition of 30°C. and 80% RH.

As shown in Table I-3, the light-sensitive material according to thepresent invention were excellent in charging properties, dark chargeretention rate and photosensitivity. Also, as a result of the evaluationon image forming performance of each light-sensitive material, it wasfound that clear duplicated images having good reproducibility of finelines and letters and no occurrence of unevenness in half tone areaswithout the formation of background fog were obtained. Further, whenthese electrophotographic light-sensitive materials were employed asoffset master plate precursors under the same printing condition asdescribed in Example I-2, more than 10,000 good prints were obtainedrespectively.

EXAMPLES I-19 TO I-22

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example I-1, except for using each of thedye shown in Table I-4 below in place of Cyanine Dye (I-I) used inExample I-1.

                                      TABLE I-4                                   __________________________________________________________________________    Example                                                                            Dye  Chemical Structure of Dye                                           __________________________________________________________________________    I-19 (I-III)                                                                             ##STR417##                                                         I-20 (I-IV)                                                                              ##STR418##                                                         I-21 (I-V)                                                                               ##STR419##                                                         I-22 (I-VI)                                                                              ##STR420##                                                         __________________________________________________________________________

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided clear duplicated images free frombackground fog even when processed under severe condition of hightemperature and high humidity (30° C. and 80% RH).

EXAMPLES I-23 AND I-24

A mixture of 6.5 g of Resin (A-2) (Example I-23) or Resin (A-7) (ExampleI-24), 33.5 g of Resin (B-8), 200 g of zinc oxide, 0.02 g of uranine,0.03 g of Methine Dye (I-VII) shown below, 0.03 g of Methine Dye(I-VIII) shown below, 0.18 g of p-hydroxybenzoic acid and 300 g oftoluene was dispersed by a homogenizer at 5×10³ r.p.m. for 8 minutes toprepare a coating composition for a light-sensitive layer. The coatingcomposition was coated on paper, which had been subjected toelectrically conductive treatment, by a wire bar at a dry coverage of 25g/m², and dried for 20 seconds at 110° C. Then, the coated material wasallowed to stand in a dark place for 24 hours under the conditions of20° C. and 65% RH to prepare each electrophotographic light-sensitivematerial. ##STR421##

COMPARATIVE EXAMPLE I-3

An electrophotographic light-sensitive material was prepared in the samemanner as in Example I-23, except for using Resin (R-I-3) shown below inplace of Resin (B-8) used in Example I-23. ##STR422##

With each of the light-sensitive materials thus prepared, variouscharacteristics were evaluated in the same manner as in Example I-2. Theresults obtained are shown in Table I-5 below.

                                      TABLE I-5                                   __________________________________________________________________________                    Example I-23                                                                         Example I-24                                                                         Comparative Example I-3                         __________________________________________________________________________    Binder Resin    (A-2)/(B-8)                                                                          (A-7)/(B-8)                                                                          (A-2)/(R-I-3)                                   Smoothness of Photoconductive                                                                 280    300    285                                             Layer (sec/cc)                                                                Electrostatic Characteristics*.sup.6)                                         I (20° C., 65% RH)                                                                     615    710    595                                             II (30° C., 80% RH)                                                                    595    695    575                                             D.R.R. (%)                                                                    I (20° C., 65% RH)                                                                     92     95     89                                              II (30° C., 80% RH)                                                                    89     93     84                                              E.sub.1/10 (lux · sec)                                               I (20° C., 65% RH)                                                                     7.6    6.2    9.6                                             II (30° C., 80% RH)                                                                    8.1    6.9    10.3                                            E.sub.1/100 (lux · sec)                                              I (20° C., 65% RH)                                                                     13     10     16                                              II (30° C., 80% RH)                                                                    18     11     18                                              Image Forming*.sup.7)                                                         Performance                                                                   I (20° C., 65% RH)                                                                     Good   Very good                                                                            Edge mark of cutting                            II (30° C., 80% RH)                                                                    Good   Very good                                                                            Edge mark of cutting,                                                         unevenness in half                                                            tone area                                       Contact Angle with Water (°)                                                           10 or less                                                                           10 or less                                                                           10 or less                                      Printing Durability                                                                           10,000 10,000 Background stain due to                                         prints prints edge mark of cutting                                                          occurred from the start                                                       of printing                                     __________________________________________________________________________

The characteristics were evaluated in the same manner as in Example I-2,except that some electrostatic characteristics and image formingperformance were evaluated according to the following test methods.

*6) Measurement of Electrostatic Characteristics: E_(1/10) and E_(1/100)

The surface of the photoconductive layer was charged to -400 V withcorona discharge, and then irradiated by visible light of theilluminance of 2.0 lux. Then, the time required for decay of the surfacepotential (V₁₀) to 1/10 or 1/100 thereof was determined, and theexposure amount E_(1/10) or E_(1/100) (lux.sec) was calculatedtherefrom.

*7) Image Forming Performance

The electrophotographic light-sensitive material was allowed to standfor one day under the ambient condition described below, thelight-sensitive material was subjected to plate making by afull-automatic plate making machine (ELP-404V manufactured by Fuji PhotoFilm Co., Ltd.) using ELP-T as a toner. The duplicated image thusobtained was visually evaluated for fog and image quality. The ambientcondition at the time of image formation was 20° C. and 65% RH (I) or30° C. and 80% RH (II). The original used for the duplication wascomposed of cuttings of other originals pasted up thereon.

From the results shown above, it can be seen that each light-sensitivematerial exhibited almost the same properties with respect to thesurface smoothness and mechanical strength of the photoconductive layer.However, on the electrostatic characteristics, the light-sensitivematerial of Comparative Example I-3 had the particularly large value ofphotosensitivity E_(1/100), and this tendency increased under the hightemperature and high humidity condition. On the contrary, theelectrostatic characteristics of the light-sensitive material accordingto the present invention were good. Further, those of Example I-24 usingthe resin (A') were very good. The value of E_(1/100) thereof wasparticularly small.

With respect to image forming performance, the edge mark of cuttingspasted up was observed as background fog in the non-image areas in thelight-sensitive material of Comparative Example I-3. On the contrary,the light-sensitive materials according to the present inventionprovided clear duplicated images free from background fog.

Further, each of these light-sensitive materials was subjected to theoil-desensitizing treatment to prepare an offset printing plate andusing the resulting plate printing was conducted. The plates accordingto the present invention provided 10,000 prints of clear image withoutbackground stains. However, with the plate of Comparative Example I-3,the above described edge mark of cuttings pasted up was not removed withthe oil-desensitizing treatment and the background stains occurred fromthe start of printing.

It can be seen from the results described above that the light-sensitivematerials according to the present invention were excellent in allaspects of the surface smoothness and mechanical strength of thephotoconductive layer, electrostatic characteristics and printingproperty. Further, it can be seen that the electrostatic characteristicsare more improved by using the resin (A').

EXAMPLE I-25

A mixture of 5 g of Resin (A-22), 35 g of Resin (B-11), 200 g of zincoxide, 0.02 g of uranine, 0.04 g of Rose Bengal, 0.03 g of bromophenolblue, 0.40 g of phthalic anhydride and 300 g of toluene was treated inthe same manner as described in Example I-23 to prepare anelectrophotographic light-sensitive material.

As the result of the evaluation of various characteristics in the samemanner as described in Example I-23, it can be seen that thelight-sensitive material according to the present invention is excellentin charging properties, dark charge retention rate and photosensitivity,and provides a clear duplicated image free from background fog undersevere conditions of high temperature and high humidity (30° C. and 80%RH). Further, when the material was employed as an offset master plateprecursor, 10,000 prints of clear image were obtained.

EXAMPLES I-26 TO I-37

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example I-25, except for using 5 g of eachof Resin (A) and 35 g of each of Resin (B) shown in Table I-6 below inplace of 5 g of Resin (A-22) and 35 g of Resin (B-11) used in ExampleI-25, respectively.

                  TABLE I-6                                                       ______________________________________                                        Example        Resin (A)    Resin (B)                                         ______________________________________                                        I-26           A-1          B-4                                               I-27           A-2          B-5                                               I-28           A-4          B-7                                               I-29           A-5          B-8                                               I-30           A-9          B-14                                              I-31           A-15         B-16                                              I-32           A-20         B-17                                              I-33           A-21         B-18                                              I-34           A-22         B-20                                              I-35           A-25         B-21                                              I-36           A-26         B-22                                              I-37           A-27         B-24                                              ______________________________________                                    

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided a clear duplicated image free frombackground fog and scratches of fine lines even under severe conditionof high temperature and high humidity (30° C. and 80% RH). Further, whenthese materials were employed as offset master plate precursors, 10,000prints of a clear image free from background stains were obtainedrespectively.

EXAMPLE II-1

A mixture of 6 g (solid basis) of Resin (A-104), 34 g (solid basis) ofResin (B-1), 200 g of photoconductive zinc oxide, 0.018 g of Cyanine Dye(II-I) shown below, 0.45 g of phthalic anhydride and 300 g of toluenewas dispersed by a homogenizer (manufactured by Nippon Seiki K.K.) at arotation of 6×10³ r.p.m. for 10 minutes to prepare a coating compositionfor a light-sensitive layer. The coating composition was coated onpaper, which had been subjected to electrically conductive treatment, bya wire bar at a dry coverage of 25 g/m², followed by drying at 110° C.for 10 seconds. The coated material was then allowed to stand in a darkplace at 20° C. and 65% RH for 24 hours to prepare anelectrophotographic light-sensitive material. ##STR423##

COMPARATIVE EXAMPLE II-1

An electrophotographic light-sensitive material was prepared in the samemanner as in Example II-1, except for using 34 g of Resin (R-II-1) shownbelow in place of 34 g of Resin (B-1) used in Example II-1. ##STR424##

COMPARATIVE EXAMPLE II-2

An electrophotographic light-sensitive material was prepared in the samemanner as in Example II-1, except for using 34 g of Resin (R-II-2) shownbelow in place of 34 g of Resin (B-1) used in Example II-1. ##STR425##

With each of the light-sensitive materials thus prepared, electrostaticcharacteristics and image forming performance were evaluated. Theresults obtained are shown in Table II-1 below.

                  TABLE II-1                                                      ______________________________________                                                    Example                                                                              Comparative                                                                              Comparative                                                 II-1   Example II-1                                                                             Example II-2                                    ______________________________________                                        Electrostatic*.sup.1)                                                         Characteristics                                                               V.sub.10 (-V)                                                                 I (20° C., 65% RH)                                                                   705      690        710                                         II (30° C., 80% RH)                                                                  690      670        690                                         III (15° C., 30% RH)                                                                 720      700        720                                         D.R.R. (90 sec value)                                                         (%)                                                                           I (20° C., 65% RH)                                                                   88       85         88                                          II (30° C., 80% RH)                                                                  83       78         84                                          III (15° C., 30% RH)                                                                 89       86         88                                          E.sub.1/10 (erg/cm.sup.2)                                                     I (20° C., 65% RH)                                                                   15.0     21         18                                          II (30° C., 80% RH)                                                                  15.3     23         20                                          III (15° C., 30% RH)                                                                 19.2     28         24                                          Image Forming*.sup.2)                                                         Performance                                                                   I (20° C., 65% RH)                                                                   Very     Good       Good                                                      good                                                            II (30° C., 80% RH)                                                                  Good     Unevenness Unevenness                                                         in half tone                                                                             in half tone                                                       area, slight                                                                             area, slight                                                       background background                                                         fog        fog                                         III (15° C., 30% RH)                                                                 Good     White spots                                                                              White spots                                                        in image   in image                                                           portion    portion                                     ______________________________________                                    

The evaluation of each item shown in Table II-1 was conducted in thefollowing manner.

*1) Electrostatic Characteristics

The light-sensitive material was charged with a corona discharge to avoltage of -6 kV for 20 seconds in a dark room using a paper analyzer("Paper Analyzer SP-428" manufactured by Kawaguchi Denki K.K.). Tenseconds after the corona discharge, the surface potential V₁₀ wasmeasured. The sample was then allowed to stand in the dark for anadditional 90 seconds, and the potential V₁₀₀ was measured. The darkdecay retention rate (DRR; %), i.e., percent retention of potentialafter dark decay for 90 seconds, was calculated from the followingequation:

    DRR(%)=(V.sub.100 /V.sub.10)×100

Separately, the surface of photoconductive layer was charged to -400 Vwith a corona discharge and then exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm), and the time required for decay of the surface potential V₁₀ toone-tenth was measured, and the exposure amount E_(1/10) (erg/cm²) wascalculated therefrom. The measurements were conducted under ambientcondition of 20° C. and 65% RH (I), 30° C. and 80% RH (II) or 15° C. and30% RH (III).

*2) Image Forming Performance

After the light-sensitive material was allowed to stand for one dayunder the ambient condition shown below, the light-sensitive materialwas charged to -6 kV and exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm; output: 2.8 mW) at an exposure amount of 64 erg/cm² (on thesurface of the photoconductive layer) at a pitch of 25 μm and a scanningspeed of 300 m/sec. The thus formed electrostatic latent image wasdeveloped with a liquid developer ("ELP-T" produced by Fuji Photo FilmCo., Ltd.), washed with a rinse solution of isoparaffinic solvent("Isopar G" manufactured by Esso Chemical K.K.) and fixed. Theduplicated image obtained was visually evaluated for fog and imagequality. The ambient condition at the time of image formation was 20° C.and 65% RH (I), 30° C. and 80% RH (II) or 15° C. and 30% RH (III).

As can be seen from the results shown in Table II-1, the light-sensitivematerial according to the present invention exhibited good electrostaticcharacteristics and provided duplicated image which was clear and freefrom background fog, even when the ambient condition was fluctuated. Onthe contrary, while the light-sensitive materials of ComparativeExamples II-1 and 11-2 exhibited good image forming performance underthe ambient condition of normal temperature and normal humidity (I), theoccurrence of unevenness of density was observed in the highly accurateimage portions, in particular, half tone areas of continuous gradationunder the ambient condition of high temperature and high humidity (II)regardress of the electrostatic characteristics. Also, a slightbackground fog remained without removing after the rinse treatment.Further, the occurrence of unevenness of small white spots at random inthe image portion was observed under the ambient condition of lowtemperature and low humidity (III).

From all these considerations, it is thus clear that anelectrophotographic light-sensitive material satisfying bothrequirements of electrostatic characteristics and image formingperformance (in particular, for highly accurate image) and beingadvantageously employed particularly in a scanning exposure system usinga semiconductor laser beam can be obtained only when the binder resinaccording to the present invention is used.

EXAMPLE II-2

A mixture of 5 g (solid basis) of Resin (A-119), 35 g (solid basis) ofResin (B-2), 200 g of photoconductive zinc oxide, 0.020 g of Methine Dye(II-II) shown below, 0.20 g of N-hydroxymalinimide and 300 g of toluenewas treated in the same manner as described in Example II-1 to preparean electrophotographic light-sensitive material. ##STR426##

COMPARATIVE EXAMPLE II-3

An electrophotographic light-sensitive material was prepared in the samemanner as in Example II-2, except for using 35 g of Resin (R-II-3) shownbelow in place of 35 g of Resin (B-2) used in Example II-2. ##STR427##

COMPARATIVE EXAMPLE II-4

An electrophotographic light-sensitive material was prepared in the samemanner as in Example II-2, except for using 35 g of Resin (R-II-4) shownbelow in place of 35 g of Resin (B-2) used in Example II-2. ##STR428##

With each of the light-sensitive materials thus-prepared, a filmproperty in terms of surface smoothness, mechanical strength,electrostatic characteristics and image forming performance wereevaluated. Further, printing property was evaluated when it was used asan electrophotographic lithographic printing plate precursor. Theresults obtained are shown in Table II-2 below.

                                      TABLE II-2                                  __________________________________________________________________________                             Comparative                                                                           Comparative                                                   Example II-2                                                                          Example II-3                                                                          Example II-4                                 __________________________________________________________________________    Smoothness of Photoconductive*.sup.3)                                                          385     870     400                                          Layer (sec/cc)                                                                Mechanical Strength of*.sup.4)                                                                 96      79      84                                           Photoconductive Layer (%)                                                     Electrostatic Characteristics                                                 V.sub.10 (-V)                                                                 I (20° C., 65% RH)                                                                      730     700     720                                          II (30° C., 80% RH)                                                                     710     665     700                                          III (15° C., 30% RH)                                                                    745     720     735                                          D.R.R. (%)                                                                    (90 sec value)                                                                I (20° C., 65% RH)                                                                      89      84      88                                           II (30° C., 80% RH)                                                                     85      79      83                                           III (15° C., 30% RH)                                                                    89      85      86                                           E.sub.1/10 (erg/cm.sup.2)                                                     I (20° C., 65% RH)                                                                      15.2    22.0    20.2                                         II (30° C., 80% RH)                                                                     16.0    25.4    21.3                                         III (15° C., 30% RH)                                                                    18.8    30.0    26.0                                         Image Forming                                                                 Performance                                                                   I (20° C., 65% RH)                                                                      Good    Good    Good                                         II (30° C., 80% RH)                                                                     Good    Unevenness in                                                                         Slight unevenness                                                     half tone area                                                                        in half tone area                            III (15° C., 30% RH)                                                                    Good    Unevenness in                                                                         Unevenness in                                                         half tone area,                                                                       half tone area,                                                       unevenness of                                                                         unevenness of                                                         white spots in                                                                        white spots in                                                        image portion                                                                         image portion                                Water Retentivity of*.sup.5)                                                                   No background                                                                         Background                                                                            Slight background                            Light-Sensitive Material                                                                       stain at all                                                                          stain   stain                                        Printing Durability*.sup.6)                                                                    10,000 prints                                                                         4,500 prints                                                                          6,000 prints                                 __________________________________________________________________________

The evaluation of each item shown in Table II-2 was conducted in thefollowing manner.

*3) Smoothness of Photoconductive Layer

The smoothness (sec/cc) of the light-sensitive material was measuredusing a Beck's smoothness test machine (manufactured by Kumagaya RikoK.K.) under an air volume condition of 1 cc.

*4) Mechanical Strength of Photoconductive Layer

The surface of the light-sensitive material was repeatedly (1000 times)rubbed with emery paper (#1000) under a load of 75 g/cm² using a Heidon14 Model surface testing machine (manufactured by Shinto Kagaku K.K.).After dusting, the abrasion loss of the photoconductive layer wasmeasured to obtain film retention (%).

*5) Water Retentivity of Light-Sensitive Material

A light-sensitive material without subjecting to plate making was passedtwice through an etching processor using an aqueous solution obtained bydiluting an oil-desensitizing solution ("ELP-EX" produced by Fuji PhotoFilm Co., Ltd.) to a five-fold volume with distilled water to conduct anoil-desensitizing treatment of the surface of the photoconductive layer.The material thus-treated was mounted on an offset printing machine("611XLA-II Model" manufactured by Hamada Printing Machine ManufacturingCo.) and printing was conducted using distilled water as dampeningwater. The extent of background stain occurred on the 50th print wasvisually evaluated. This tesing method corresponds to evaluation ofwater retentivity after oil-desensitizing treatment of thelight-sensitive material under the forced condition.

*6) Printing Durability

The light-sensitive material was subjected to plate making in the samemanner as described in *2) above to form toner images, and the surfaceof the photoconductive layer was subjected to oil-desensitizationtreatment by passing twice through an etching processor using ELP-EX.The resulting lithographic printing plate was mounted on an offsetprinting machine ("Oliver Model 52", manufactured by Sakurai SeisakushoK.K.), and printing was carried out on paper. The number of printsobtained until background stains in the non-image areas appeared or thequality of the image areas was deteriorated was taken as the printingdurability. The larger the number of the prints, the higher the printingdurability.

As can be seen from the results shown in Table II-2, the light-sensitivematerial according to the present invention had good surface smoothness,film strength and electrostatic characteristics of the photoconductivelayer. The duplicated image obtained was clear and free from backgroundfog in the non-image area. These results appear to be due to sufficientadsorption of the binder resin onto the photoconductive substance andsufficient covering of the surface of the particles with the binderresin. For the same reason, when it was used as an offset master plateprecursor, oil-desensitization of the offset master plate precursor withan oil-desensitizing solution was sufficient to render the non-imageareas satisfactorily hydrophilic and adhesion of ink was not observed atall as a result of the evaluation of water retentivity under the forcedcondition. On practical printing using the resulting master plate,10,000 prints of clear image without background stains were obtained.

On the contrary, with the light-sensitive materials of ComparativeExamples II-3 and II-4, the occurrence of slight background stain innon-image area, unevenness in highly accurate image of continuousgradation and unevenness of white spots in image portion was observedwhen the image formation was conducted under severe conditions. Further,as a result of the test on water retentivity of these light-sensitivematerials to make offset master plates, the adhesion of ink wasobserved. The printing durability thereof was at most 4,000 to 6,000prints.

From these results it is believed that the resin (A) and the resin (B)according to the present invention suitably interacts with zinc oxideparticles to form the condition under which an oil-desensitizingreaction proceeds easily and sufficiently with an oil-desensitizingsolution and that the remarkable improvement in film strength isachieved by the action of the resin (B).

EXAMPLES II-3 TO II-22

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example II-2, except for using each ofResins (A) and Resins (B) shown in Table II-3 below in place of Resin(A-119) and Resin (B-2) used in Example II-2, respectively.

                  TABLE II-3                                                      ______________________________________                                        Example        Resin (A)    Resin (B)                                         ______________________________________                                        II-3           A-103        B-3                                               II-4           A-104        B-4                                               II-5           A-105        B-5                                               II-6           A-106        B-6                                               II-7           A-108        B-7                                               II-8           A-109        B-8                                               II-9           A-111        B-9                                               II-10          A-112        B-10                                              II-11          A-116        B-11                                              II-12          A-118        B-12                                              II-13          A-119        B-13                                              II-14          A-120        B-14                                              II-15          A-121        B-15                                              II-16          A-122        B-16                                              II-17          A-123        B-17                                              II-18          A-124        B-18                                              II-19          A-128        B-19                                              II-20          A-130        B-20                                              II-21          A-131        B-22                                              II-22          A-133        B-24                                              ______________________________________                                    

The electrostatic characteristics and image forming performance of eachof the light-sensitive materials were determined in the same manner asdescribed in Example II-1. Each light-sensitive material exhibited goodelectrostatic characteristics. As a result of the evaluation on imageforming performance of each light-sensitive material, it was found thatclear duplicated images having good reproducibility of fine lines andletters and no occurrence of unevenness in half tone areas without theformation of background fog were obtained.

Further, when these electrophotographic light-sensitive materials wereemployed as offset master plate precursors under the same printingcondition as described in Example II-2, more than 10,000 good printswere obtained respectively.

It can be seen from the results described above that each of thelight-sensitive materials according to the present invention wassatisfactory in all aspects of the surface smoothness and film strengthof the photoconductive layer, electrostatic characteristics and printingproperty.

EXAMPLES II-23 TO II-26

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example II-1, except for using each of thedye shown in Table II-4 below in place of Cyanine Dye (II-1) used inExample II-1.

                                      TABLE II-4                                  __________________________________________________________________________    Example                                                                            Dye  Chemical Structure of Dye                                           __________________________________________________________________________    II-23                                                                              (II-III)                                                                            ##STR429##                                                         II-24                                                                              (II-IV)                                                                             ##STR430##                                                         II-25                                                                              (II-V)                                                                              ##STR431##                                                         II-26                                                                              (II-VI)                                                                             ##STR432##                                                         __________________________________________________________________________

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided clear duplicated images free frombackground fog even when processed under severe conditions of hightemperature and high humidity (30° C. and 80% RH) and low temperatureand low humidity (15° C. and 30% RH).

EXAMPLES II-27 AND II-28

A mixture of 6.5 g of Resin (A-101) (Example II-27) or Resin (A-119)(Example II-28), 33.5 g of Resin (B-18), 200 g of zinc oxide, 0.02 g ofuranine, 0.03 g of Methine Dye (II-VII) shown below, 0.03 g of MethineDye (II-VIII) shown below, 0.18 g of p-hydroxybenzoic acid and 300 g oftoluene was dispersed by a homogenizer at a rotation of 7×10³ r.p.m. for10 minutes to prepare a coating composition for a light-sensitive layer.The coating composition was coated on paper, which had been subjected toelectrically conductive treatment, by a wire bar at a dry coverage of 25g/m², and dried for 20 seconds at 110° C. Then, the coated material wasallowed to stand in a dark place for 24 hours under the conditions of20° C. and 65% RH to prepare each electrophotographic light-sensitivematerial. ##STR433##

COMPARATIVE EXAMPLE II-5

An electrophotographic light-sensitive material was prepared in the samemanner as in Example II-27, except for using 33.5 g of Resin (R-II-5)shown below in place of 33.5 g of Resin (B-18) used in Example II-27.##STR434##

With each of the light-sensitive materials thus prepared, variouscharacteristics were evaluated in the same manner as in Example II-2.The results obtained are shown in Table II-5 below.

                                      TABLE II-5                                  __________________________________________________________________________                    Example II-27                                                                         Example II-28                                                                         Comparative Example II-5                      __________________________________________________________________________    Binder Resin    (A-101)/(B-18)                                                                        (A-119)/(B-18)                                                                        (A-101)/(R-II-5)                              Smoothness of Photoconductive                                                                 440     445     450                                           Layer (sec/cc)                                                                Mechanical Strength of                                                                        95      96      83                                            Photoconductive Layer (%)                                                     Electrostatic Characteristics*.sup.7)                                         V.sub.10 (-V)                                                                 I (20° C., 65% RH)                                                                     610     715     595                                           II (30° C., 80% RH)                                                                    580     690     580                                           III (15° C., 30% RH)                                                                   635     730     605                                           D.R.R. (%)                                                                    I (20° C., 65% RH)                                                                     90      96      88                                            II (30° C., 80% RH)                                                                    86      93      84                                            III (15° C., 30% RH)                                                                   91      96      88                                            E.sub.1/10  (lux · sec)                                              I (20° C., 65% RH)                                                                     10.5    8.6     11.3                                          II (30° C., 80% RH)                                                                    9.8     9.2     10.6                                          III (15° C., 30% RH)                                                                   12.8    10.3    14.6                                          Image Forming*.sup.8)                                                         Performance                                                                   I (20° C., 65% RH)                                                                     Good    Very good                                                                             Good                                          II (30° C., 80% RH)                                                                    Good    Very good                                                                             Edge mark of cutting,                                                         unevenness in half                                                            tone area                                     III (15° C., 30% RH)                                                                   Good    Very good                                                                             Edge mark of cutting,                                                         unevenness in image                                                           portion                                       Water Retentivity of                                                                          Good    Good    Slight background stain                       Light-Sensitive Material                                                      Printing Durability                                                                           10,000  10,000  Background stain from                                         prints  prints  the start of printing                         __________________________________________________________________________

The characteristics were evaluated in the same manner as in ExampleII-2, except that some electrostatic characteristics and image formingperformance were evaluated according to the following test methods.

*7) Measurement of Electrostatic Characteristics: E_(1/10)

The surface of the photoconductive layer was charged to -400 V withcorona discharge, and then irradiated by visible light of theilluminance of 2.0 lux. Then, the time required for decay of the surfacepotential (V₁₀) to 1/10 thereof was determined, and the exposure amountE_(1/10) (lux.sec) was calculated therefrom.

*8) Image Forming Performance

The electrophotographic light-sensitive material was allowed to standfor one day under the ambient condition described below, thelight-sensitive material was subjected to plate making by afull-automatic plate making machine (ELP-404V manufactured by Fuji PhotoFilm Co., Ltd.) using ELP-T as a toner. The duplicated image thusobtained was visually evaluated for fog and image quality. The ambientcondition at the time of image formation was 20° C. and 65% RH (I), 30°C. and 80% RH (II) or 15° C. and 30% RH (III). The original used for theduplication was composed of cuttings of other originals pasted upthereon.

From the results, it can be seen that each of the light-sensitivematerials according to the present invention exhibited good mechanicalstrength of the photoconductive layer. On the contrary, with thelight-sensitive material of Comparative Example II-5 the value ofmechanical strength was lower than them, and the value of E_(1/10) ofelectrostatic characteristics degraded particularly under the ambientcondition of low temperature and low humidity (III), while they weregood under the ambient condition of normal temperature and normalhumidity (I). On the other hand, the electrostatic characteristics ofthe light-sensitive materials according to the present invention weregood. Particularly, those of Example II-28 using the resin (A') werevery good. The value of E_(1/100) thereof was particularly small.

With respect to image forming performance, the edge mark of cuttingspasted up was observed as background fog in the non-image areas in thelight-sensitive material of Comparative Example II-5. Also, theoccurrence of unevenness in half tone area of continuous gradation andunevenness of small white spots in image portion was observed on theduplicated image when the ambient conditions at the time of the imageformation were high temperature and high humidity (II) and lowtemperature and low humidity (III).

Further, each of these light-sensitive materials was subjected to theoil-desensitizing treatment to prepare an offset printing plate andusing the plate printing was conducted. The plates according to thepresent invention provided 10,000 prints of clear image withoutbackground stains. However, with the plate of Comparative Example II-5,the above described edge mark of cuttings pasted up was not removed withthe oil-desensitizing treatment and the background stains occurred fromthe start of printing.

It can be seen from the results described above that only thelight-sensitive materials according to the present invention can provideexcellent performance.

EXAMPLE II-29

A mixture of 5 g of Resin (A-104), 35 g of Resin (B-22), 200 g of zincoxide, 0.02 g of uranine, 0.04 g of Rose Bengal, 0.03 g of bromophenolblue, 0.40 g of phthalic anhydride and 300 g of toluene was treated inthe same manner as described in Example II-27 to prepare anelectrophotographic light-sensitive material.

As the result of the evaluation of various characteristics in the samemanner as described in Example II-27, it can be seen that thelight-sensitive material according to the present invention is excellentin charging properties, dark charge retention rate and photosensitivity,and provides a clear duplicated image free from background fog undersevere conditions of high temperature and high humidity (30° C. and 80%RH) and low temperature and low humidity (15° C. and 30% RH). Further,when the material was employed as an offset master plate precursor,10,000 prints of clear image were obtained.

EXAMPLES II-30 TO II-53

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example II-29, except for using 5 g of eachof Resin (A) and 35 g of each of Resin (B) shown in Table II-6 below inplace of 5 g of Resin (A-104) and 35 g of Resin (B-22) used in ExampleII-29, respectively.

                  TABLE II-6                                                      ______________________________________                                        Example        Resin (A)    Resin (B)                                         ______________________________________                                        II-30          A-101        B-1                                               II-31          A-102        B-2                                               II-32          A-103        B-3                                               II-33          A-104        B-4                                               II-34          A-105        B-5                                               II-35          A-106        B-6                                               II-36          A-107        B-7                                               II-37          A-108        B-8                                               II-38          A-109        B-9                                               II-39          A-110        B-9                                               II-40          A-112        B-10                                              II-41          A-113        B-11                                              II-42          A-114        B-12                                              II-43          A-115        B-10                                              II-44          A-116        B-13                                              II-45          A-117        B-14                                              II-46          A-118        B-15                                              II-47          A-119        B-16                                              II-48          A-120        B-17                                              II-49          A-121        B-18                                              II-50          A-122        B-19                                              II-51          A-125        B-20                                              II-52          A-127        B-21                                              II-53          A-129        B-23                                              ______________________________________                                    

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided a clear duplicated image free frombackground fog and scratches of fine lines even under severe conditionsof high temperature and high humidity (30° C. and 80% RH) and lowtemperature and low humidity (15° C. and 30% RH). Further, when thesematerials were employed as offset master plate precursors, 10,000 printsof a clear image free from background stains were obtained respectively.

EXAMPLE III-1

A mixture of 5 g (solid basis) of Resin (A-205), 35 g (solid basis) ofResin (B-1), 200 g of photoconductive zinc oxide, 0.018 g of Cyanine Dye(III-I) shown below, 0.15 g of phthalic anhydride and 300 g of toluenewas dispersed by a homogenizer (manufactured by Nippon Seiki K.K.) at arotation of 6×10³ r.p.m. for 6 minutes to prepare a coating compositionfor a light-sensitive layer. The coating composition was coated onpaper, which had been subjected to electrically conductive treatment, bya wire bar at a dry coverage of 25 g/m², followed by drying at 110° C.for 10 seconds. The coated material was then allowed to stand in a darkplace at 20° C. and 65% RH for 24 hours to prepare anelectrophotographic light-sensitive material. ##STR435##

COMPARATIVE EXAMPLE III-1

An electrophotographic light-sensitive material was prepared in the samemanner as in Example III-1, except for using 35 g of Resin (R-III-1)shown below in place of 35 g of Resin (B-1) used in Example III-1.##STR436##

COMPARATIVE EXAMPLE III-2

An electrophotographic light-sensitive material was prepared in the samemanner as in Example III-1, except for using 35 g of Resin (R-III-2)shown below in place of 35 g of Resin (B-1) used in Example III-1.##STR437##

With each of the light-sensitive materials thus prepared, electrostaticcharacteristics and image forming performance were evaluated. Theresults obtained are shown in Table III-1 below.

                  TABLE III-1                                                     ______________________________________                                                                      Comparative                                                Example                                                                              Comparative Example                                                    III-1  Example III-1                                                                             III-2                                           ______________________________________                                        Electrostatic*.sup.1)                                                         Characteristics                                                               V.sub.10 (-V)                                                                 I (20° C., 65% RH)                                                                  790      760         775                                         II (30° C., 80% RH)                                                                 775      730         760                                         III (15° C., 30% RH)                                                                785      760         780                                         D.R.R. (90 sec value)                                                         (%)                                                                           I (20° C., 65% RH)                                                                  90       85          88                                          II (30° C., 80% RH)                                                                 86       79          85                                          III (15° C., 30% RH)                                                                89       84          87                                          E.sub.1/10  (erg/cm.sup.2)                                                    I (20° C., 65% RH)                                                                  21       33          28                                          II (30° C., 80% RH)                                                                 19       30          25                                          III (15° C., 30% RH)                                                                27       41          37                                          Image Forming*.sup.2)                                                         Performance                                                                   I (20° C., 65% RH)                                                                  Very     Good        Good                                                     good                                                             II (30° C., 80% RH)                                                                 Good     Unevenness  Unevenness                                                        in half tone                                                                              in half tone                                                      area, slight                                                                              area                                                              background fog                                          III (15° C., 30% RH)                                                                Good     White spots White spots                                                       in image    in image                                                          portion     portion                                     ______________________________________                                    

The evaluation of each item shown in Table III-1 was conducted in thefollowing manner.

*1) Electrostatic Characteristics

The light-sensitive material was charged with a corona discharge to avoltage of -6 kV for 20 seconds in a dark room using a paper analyzer("Paper Analyzer SP-428" manufactured by Kawaguchi Denki K.K.). Tenseconds after the corona discharge, the surface potential V₁₀ wasmeasured. The sample was then allowed to stand in the dark for anadditional 90 seconds, and the potential V₁₀₀ was measured. The darkdecay retention rate (DRR; %), i.e., percent retention of potentialafter dark decay for 90 seconds, was calculated from the followingequation:

    DRR(%)=(V.sub.100 /V.sub.10)×100

Separately, the surface of photoconductive layer was charged to -400 Vwith a corona discharge and then exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm), and the time required for decay of the surface potential V₁₀ toone-tenth was measured, and the exposure amount E_(1/10) (erg/cm²) wascalculated therefrom. The measurements were conducted under ambientcondition of 20° C. and 65% RH (I), 30° C. and 80% RH (II) or 15° C. and30% RH (III).

*2) Image Forming Performance

After the light-sensitive material was allowed to stand for one dayunder the ambient condition shown below, the light-sensitive materialwas charged to -6 kV and exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm; output: 2.8 mW) at an exposure amount of 64 erg/cm² (on thesurface of the photoconductive layer) at a pitch of 25 μm and a scanningspeed of 300 m/sec. The thus formed electrostatic latent image wasdeveloped with a liquid developer ("ELP-T" produced by Fuji Photo FilmCo., Ltd.), washed with a rinse solution of isoparaffinic solvent("Isopar G" manufactured by Esso Chemical K.K.) and fixed. Theduplicated image obtained was visually evaluated for fog and imagequality. The ambient condition at the time of image formation was 20° C.and 65% RH (I), 30° C. and 80% RH (II) or 15° C. and 30% RH (III).

As can be seen from the results shown in Table III-1, thelight-sensitive material according to the present invention exhibitedgood electrostatic characteristics and provided duplicated image whichwas clear and free from background fog, even when the ambient conditionwas fluctuated. On the contrary, while the light-sensitive materials ofComparative Examples III-1 and III-2 exhibited good image formingperformance under the ambient condition of normal temperature and normalhumidity (I), the occurrence of unevenness of density was observed inthe highly accurate image portions, in particular, half tone areas ofcontinuous gradation under the ambient condition of high temperature andhigh humidity (II) regardress of the electrostatic characteristics.Also, a slight background fog remained without removing after the rinsetreatment. Further, the occurrence of unevenness of small white spots atrandom in the image portion was observed under the ambient condition oflow temperature and low humidity (III).

From all these considerations, it is thus clear that anelectrophotographic light-sensitive material satisfying bothrequirements of electrostatic characteristics and image formingperformance (in particular, for highly accurate image) and beingadvantageously employed particularly in a scanning exposure system usinga semiconductor laser beam can be obtained only when the binder resinaccording to the present invention is used.

EXAMPLE III-2

A mixture of 6 g (solid basis) of Resin (A-221), 34 g (solid basis) ofResin (B-2), 200 g of photoconductive zinc oxide, 0.020 g of Methine Dye(III-II) shown below, 0.20 g of N-hydroxymaleinimide and 300 g oftoluene was treated in the same manner as described in Example III-1 toprepare an electrophotographic light-sensitive material. ##STR438##

COMPARATIVE EXAMPLE III-3

An electrophotographic light-sensitive material was prepared in the samemanner as in Example III-2, except for using 34 g of Resin (R-III-3)shown below in place of 34 g of Resin (B-2) used in Example III-2.##STR439##

COMPARATIVE EXAMPLE III-4

An electrophotographic light-sensitive material was prepared in the samemanner as in Example III-2, except for using 34 g of Resin (R-III-4)shown below in place of 34 g of Resin (B-2) used in Example III-2.##STR440##

With each of the light-sensitive materials thus-prepared, a filmproperty in terms of surface smoothness, mechanical strength,electrostatic characteristics and image forming performance wereevaluated. Further, printing property was evaluated when it was used asan electrophotographic lithographic printing plate precursor. Theresults obtained are shown in Table III-2 below.

                                      TABLE III-2                                 __________________________________________________________________________                             Comparative                                                                           Comparative                                                   Example III-2                                                                         Example III-3                                                                         Example III-4                                __________________________________________________________________________    Smoothness of Photoconductive*.sup.3)                                                          380     400     365                                          Layer (sec/cc)                                                                Mechanical Strength of*.sup.4)                                                                  93      78      84                                          Photoconductive Layer (%)                                                     Electrostatic Characteristics                                                 V.sub.10 (-V)                                                                 I (20° C., 65% RH)                                                                      780     745     770                                          II (30° C., 80% RH)                                                                     760     720     750                                          III (15° C., 30% RH)                                                                    785     740     770                                          D.R.R. (%)                                                                    (90 sec value)                                                                I (20° C., 65% RH)                                                                       88      84      88                                          II (30° C., 80% RH)                                                                      84      78      83                                          III (15° C., 30% RH)                                                                     87      85      86                                          E.sub.1/10  (erg/cm.sup.2)                                                    I (20° C., 65% RH)                                                                       23      38      34                                          II (30° C., 80% RH)                                                                      20      33      30                                          III (15° C., 30% RH)                                                                     30      42      38                                          Image Forming                                                                 Performance                                                                   I (20° C., 65% RH)                                                                      Good    Good    Good                                         II (30° C., 80% RH)                                                                     Good    Unevenness in                                                                         Unevenness in                                                         half tone area                                                                        half tone area                               III (15° C., 30% RH)                                                                    Good    Unevenness of                                                                         Unevenness of                                                         white spots in                                                                        white spots in                                                        image portion                                                                         image portion                                Water Retentivity of*.sup.5)                                                                   Good    Background                                                                            Slight background                            Light-Sensitive Material stain   stain                                        Printing Durability*.sup.6)                                                                    10,000  3,000   6,000                                                         prints  prints  prints                                       __________________________________________________________________________

The evaluation of each item shown in Table III-2 was conducted in thefollowing manner.

*3) Smoothness of Photoconductive Layer

The smoothness (sec/cc) of the light-sensitive material was measuredusing a Beck's smoothness test machine (manufactured by Kumagaya RikoK.K.) under an air volume condition of 1 cc.

*4) Mechanical Strength of Photoconductive Layer

The surface of the light-sensitive material was repeatedly (1000 times)rubbed with emery paper (#1000) under a load of 75 g/cm² using a Heidon14 Model surface testing machine (manufactured by Shinto Kagaku K.K.).After dusting, the abrasion loss of the photoconductive layer wasmeasured to obtain film retention (%).

*5) Water Retentivity of Light-Sensitive Material

A light-sensitive material without subjecting to plate making was passedtwice through an etching processor using an aqueous solution obtained bydiluting an oil-desensitizing solution ("ELP-EX" produced by Fuji PhotoFilm Co., Ltd.) to a five-fold volume with distilled water to conduct anoil-desensitizing treatment of the surface of the photoconductive layer.The material thus-treated was mounted on an offset printing machine("611XLA-II Model" manufactured by Hamada Printing Machine ManufacturingCo.) and printing was conducted using distilled water as dampeningwater. The extent of background stain occurred on the 50th print wasvisually evaluated. This tesing method corresponds to evaluation ofwater retentivity after oil-desensitizing treatment of thelight-sensitive material under the forced condition.

*6) Printing Durability

The light-sensitive material was subjected to plate making in the samemanner as described in *2) above to form toner images, and the surfaceof the photoconductive layer was subjected to oil-desensitizationtreatment by passing twice through an etching processor using ELP-EX.The resulting lithographic printing plate was mounted on an offsetprinting machine ("Oliver Model 52", manufactured by Sakurai SeisakushoK.K.), and printing was carried out on paper. The number of printsobtained until background stains in the non-image areas appeared or thequality of the image areas was deteriorated was taken as the printingdurability. The larger the number of the prints, the higher the printingdurability.

As can be seen from the results shown in Table III-2, thelight-sensitive material according to the present invention had goodsurface smoothness, film strength and electrostatic characteristics ofthe photoconductive layer. The duplicated image obtained was clear andfree from background fog in the non-image area. These results appear tobe due to sufficient adsorption of the binder resin onto thephotoconductive substance and sufficient covering of the surface of theparticles with the binder resin. For the same reason, when it was usedas an offset master plate precursor, oil-desensitization of the offsetmaster plate precursor with an oil-desensitizing solution was sufficientto render the non-image areas satisfactorily hydrophilic and adhesion ofink was not observed at all as a result of the evaluation of waterretentivity under the forced condition. On practical printing using theresulting master plate, 10,000 prints of clear image without backgroundstains were obtained.

On the contrary, with the light-sensitive materials of ComparativeExamples III-3 and III-4, the occurrence of slight background stain innon-image area, unevenness in highly accurate image of continuousgradation and unevenness of white spots in image portion was observedwhen the image formation was conducted under severe conditions. Further,as a result of the test on water retentivity of these light-sensitivematerials to make offset master plates, the adhesion of ink wasobserved. The printing durability thereof was at most 3,000 to 6,000prints.

From these results it is believed that the resin (A) and the resin (B)according to the present invention suitably interacts with zinc oxideparticles to form the condition under which an oil-desensitizingreaction proceeds easily and sufficiently with an oil-desensitizingsolution and that the remarkable improvement in film strength isachieved by the action of the resin (B).

EXAMPLES III-3 TO III-22

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example III-2, except for using each ofResins (A) and Resins (B) shown in Table. III-3 below in place of Resin(A-221) and Resin (B-2) used in Example III-2, respectively.

                  TABLE III-3                                                     ______________________________________                                        Example        Resin (A)    Resin (B)                                         ______________________________________                                        III-3          A-206        B-4                                               III-4          A-207        B-7                                               III-5          A-208        B-8                                               III-6          A-209        B-9                                               III-7          A-210        B-10                                              III-8          A-211        B-11                                              III-9          A-212        B-12                                              III-10         A-213        B-13                                              III-11         A-214        B-14                                              III-12         A-215        B-15                                              III-13         A-216        B-16                                              III-14         A-218        B-17                                              III-15         A-221        B-19                                              III-16         A-222        B-20                                              III-17         A-223        B-21                                              III-18         A-203        B-22                                              III-19         A-204        B-23                                              III-20         A-223        B-24                                              III-21         A-218        B-18                                              III-22         A-214        B-16                                              ______________________________________                                    

The electrostatic characteristics and image forming performance of eachof the light-sensitive materials were determined in the same manner asdescribed in Example III-1. Each light-sensitive material exhibited goodelectrostatic characteristics. As a result of the evaluation on imageforming performance of each light-sensitive material, it was found thatclear duplicated images having good reproducibility of fine lines andletters and no occurrence of unevenness in half tone areas without theformation of background fog were obtained.

Further, when these electrophotographic light-sensitive materials wereemployed as offset master plate precursors under the same printingcondition as described in Example III-2, more than 10,000 good printswere obtained respectively.

It can be seen from the results described above that each of thelight-sensitive materials according to the present invention wassatisfactory in all aspects of the surface smoothness and film strengthof the photoconductive layer, electrostatic characteristics and printingproperty.

EXAMPLES III-23 TO III-26

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example III-1, except for using each of thedye shown in Table III-4 below in place of Cyanine Dye (III-I) used inExample III-1.

                                      TABLE III-4                                 __________________________________________________________________________    Example                                                                            Dye  Chemical Structure of Dye                                           __________________________________________________________________________    III-23                                                                             (III-III)                                                                           ##STR441##                                                         III-24                                                                             (III-IV)                                                                            ##STR442##                                                         III-25                                                                             (III-V)                                                                             ##STR443##                                                         III-26                                                                             (III-VI)                                                                            ##STR444##                                                         __________________________________________________________________________

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided clear duplicated images free frombackground fog even when processed under severe conditions of hightemperature and high humidity (30° C. and 80% RH) and low temperatureand low humidity (15° C. and 30% RH).

EXAMPLES III-27 AND III-28

A mixture of 6.5 g of Resin (A-201) (Example III-27) or Resin (A-207)(Example III-28), 33.5 g of Resin (B-16), 200 g of zinc oxide, 0.02 g ofuranine, 0.03 g of Methine Dye (III-VII) shown below, 0.03 g of MethineDye (III-VIII) shown below, 0.18 g of p-hydroxybenzoic acid and 300 g oftoluene was dispersed by a homogenizer at a rotation of 7×10³ r.p.m. for5 minutes to prepare a coating composition for a light-sensitive layer.The coating composition was coated on paper, which had been subjected toelectrically conductive treatment, by a wire bar at a dry coverage of 25g/m², and dried for 20 seconds at 110° C. Then, the coated material wasallowed to stand in a dark place for 24 hours under the conditions of20° C. and 65% RH to prepare each electrophotographic light-sensitivematerial. ##STR445##

COMPARATIVE EXAMPLE III-5

An electrophotographic light-sensitive material was prepared in the samemanner as in Example III-27, except for using 33.5 g of Resin (R-III-5)shown below in place of 33.5 g of Resin (B-16) used in Example III-27.##STR446##

With each of the light-sensitive materials thus prepared, variouscharacteristics were evaluated in the same manner as in Example III-2.The results obtained are shown in Table III-5 below.

                                      TABLE III-5                                 __________________________________________________________________________                    Example III-27                                                                        Example III-28                                                                        Comparative Example III-5                     __________________________________________________________________________    Binder Resin    (A-201)/(B-16)                                                                        (A-207)/(B-16)                                                                        (A-201)/(R-III-5)                             Smoothness of Photoconductive                                                                 300     310     310                                           Layer (sec/cc)                                                                Mechanical Strength of                                                                        93      94      86                                            Photoconductive Layer (%)                                                     Electrostatic Characteristics*.sup.7)                                         V.sub.10 (-V)                                                                 I (20° C., 65% RH)                                                                     580     745     555                                           II (30° C., 80% RH)                                                                    565     730     540                                           III (15° C., 30% RH)                                                                   580     750     550                                           D.R.R. (%)                                                                    I (20° C., 65% RH)                                                                     88      93      86                                            II (30° C., 80% RH)                                                                    84      90      81                                            III (15° C., 30% RH)                                                                   87      92      85                                            E.sub.1/10  (lux · sec)                                              I (20° C., 65% RH)                                                                     12.0    8.8     13.8                                          II (30° C., 80% RH)                                                                    11.3    8.4     13.4                                          III (15° C., 30% RH)                                                                   12.6    9.7     14.9                                          Image Forming*.sup.8)                                                         Performance                                                                   I (20° C., 65% RH)                                                                     Good    Very good                                                                             Slight edge mark                                                              of cutting                                    II (30° C., 80% RH)                                                                    Good    Very good                                                                             Unevenness in half                                                            tone area                                     III (15° C., 30% RH)                                                                   Good    Very good                                                                             Unevenness of white                                                           spots in image portion                        Water Retentivity of                                                                          Good    Good    Slight background stain                       Light-Sensitive Material                                                      Printing Durability                                                                           10,000  10,000  Background stain from                                         prints  prints  the start of printing                         __________________________________________________________________________

The characteristics were evaluated in the same manner as in ExampleIII-2, except that some electrostatic characteristics and image formingperformance were evaluated according to the following test methods.

*7) Measurement of Electrostatic Characteristics: E_(1/10)

The surface of the photoconductive layer was charged to -400 V withcorona discharge, and then irradiated by visible light of theilluminance of 2.0 lux. Then, the time required for decay of the surfacepotential (V₁₀) to 1/10 thereof was determined, and the exposure amountE_(1/10) (lux·sec) was calculated therefrom.

*8) Image Forming Performance

The electrophotographic light-sensitive material was allowed to standfor one day under the ambient condition described below, thelight-sensitive material was subjected to plate making by afull-automatic plate making machine (ELP-404V manufactured by Fuji PhotoFilm Co., Ltd.) using ELP-T as a toner. The duplicated image thusobtained was visually evaluated for fog and image quality. The ambientcondition at the time of image formation was 20° C. and 65% RH (I), 30°C. and 80% RH (II) or 15° C. and 30% RH (III). The original used for theduplication was composed of cuttings of other originals pasted upthereon.

From the results, it can be seen that each of the light-sensitivematerials according to the present invention exhibited good mechanicalstrength of the photoconductive layer. On the contrary, with thelight-sensitive material of Comparative Example III-5 the value ofmechanical strength was lower than them, and the value of E_(1/10) ofelectrostatic characteristics degraded particularly under the ambientcondition of low temperature and low humidity (III), while they weregood under the ambient condition of normal temperature and normalhumidity (I). On the other hand, the electrostatic characteristics ofthe light-sensitive materials according to the present invention weregood. Particularly, those of Example III-28 using the resin (A') werevery good. The value of E_(1/10) thereof was particularly small.

With respect to image forming performance, the edge mark of cuttingspasted up was observed as background fog in the non-image areas in thelight-sensitive material of Comparative Example III-5. Also, theoccurrence of unevenness in half tone area of continuous gradation andunevenness of small white spots in image portion was observed on theduplicated image when the ambient conditions at the time of the imageformation were high temperature and high humidity (II) and lowtemperature and low humidity (III). On the contrary, the light-sensitivematerials according to the present invention provided clear images freefrom background fog.

Further, each of these light-sensitive materials was subjected to theoil-desensitizing treatment to prepare an offset printing plate andusing the resulting plate printing was conducted. The plates accordingto the present invention provided 10,000 prints of clear image withoutbackground stains. However, with the plate of Comparative Example III-5,the above described edge mark of cuttings pasted up was not removed withthe oil-desensitizing treatment and the background stains occurred fromthe start of printing.

It can be seen from the results described above that the light-sensitivematerials according to the present invention was satisfactory in allaspects of the surface smoothness and film strength of thephotoconductive layer, electrostatic characteristics and printingproperty. Further, it can be seen that the electrostatic characteristicsare further improved by the use of the resin (A').

EXAMPLE III-29

A mixture of 5 g of Resin (A-223), 35 g of Resin (B-22), 200 g of zincoxide, 0.02 g of uranine, 0.04 g of Rose Bengal, 0.03 g of bromophenolblue, 0.40 g of phthalic anhydride and 300 g of toluene was treated inthe same manner as described in Example III-27 to prepare anelectrophotographic light-sensitive material.

As the result of the evaluation of various characteristics in the samemanner as described in Example III-27, it can be seen that thelight-sensitive material according to the present invention is excellentin charging properties, dark charge retention rate and photosensitivity,and provides a clear duplicated image free from background fog undersevere conditions of high temperature and high humidity (30° C. and 80%RH) and low temperature and low humidity (15° C. and 30% RH). Further,when the material was employed as an offset master plate precursor,10,000 prints of clear image were obtained.

EXAMPLES III-30 TO III-53

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example III-29, except for using 5 g of eachof Resin (A) and 35 g of each of Resin (B) shown in Table III-6 below inplace of 5 g of Resin (A-223) and 35 g of Resin (B-22) used in ExampleIII-29, respectively.

                  TABLE III-6                                                     ______________________________________                                        Example        Resin (A)    Resin (B)                                         ______________________________________                                        III-30         A-201        B-1                                               III-31         A-202        B-5                                               III-32         A-203        B-6                                               III-33         A-204        B-7                                               III-34         A-206        B-9                                               III-35         A-207        B-10                                              III-36         A-208        B-12                                              III-37         A-209        B-13                                              III-38         A-210        B-14                                              III-39         A-211        B-15                                              III-40         A-212        B-16                                              III-41         A-213        B-17                                              III-42         A-214        B-18                                              III-43         A-215        B-19                                              III-44         A-216        B-20                                              III-45         A-217        B-21                                              III-46         A-218        B-22                                              III-47         A-219        B-23                                              III-48         A-220        B-24                                              III-49         A-221        B-16                                              III-50         A-222        B-21                                              III-51         A-223        B-2                                               III-52         A-221        B-8                                               III-53         A-214        B-7                                               ______________________________________                                    

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided a clear duplicated image free frombackground fog and scratches of fine lines even under severe conditionsof high temperature and high humidity (30° C. and 80% RH) and lowtemperature and low humidity (15° C. and 30% RH). Further, when thesematerials were employed as offset master plate precursors, 10,000 printsof a clear image free from background stains were obtained respectively.

EXAMPLE IV-1

A mixture of 6 g (solid basis) of Resin (A-7), 34 g (solid basis) ofResin (B-101), 200 g of photoconductive zinc oxide, 0.018 g of CyanineDye (IV-I) shown below, 0.15 g of phthalic anhydride and 300 g oftoluene was dispersed by a homogenizer (manufactured by Nippon SeikiK.K.) at a rotation of 6×10³ r.p.m. for 10 minutes to prepare a coatingcomposition for a light-sensitive layer. The coating composition wascoated on paper, which had been subjected to electrically conductivetreatment, by a wire bar at a dry coverage of 18 g/m², followed bydrying at 110° C. for 10 seconds. The coated material was then allowedto stand in a dark place at 20° C. and 65% RH for 24 hours to prepare anelectrophotographic light-sensitive material. ##STR447##

COMPARATIVE EXAMPLE IV-1

An electrophotographic light-sensitive material was prepared in the samemanner as in Example IV-1, except for using 34 g of Resin (R-IV-1) shownbelow in place of 34 g of Resin (B-101) used in Example IV-1. ##STR448##

COMPARATIVE EXAMPLE IV-2

An electrophotographic light-sensitive material was prepared in the samemanner as in Example IV-1, except for using 34 g of Resin (R-IV-2) shownbelow in place of 34 g of Resin (B-101) used in Example IV-1. ##STR449##

With each of the light-sensitive materials thus prepared, electrostaticcharacteristics and image forming performance were evaluated. Theresults obtained are shown in Table IV-1 below.

                  TABLE IV-1                                                      ______________________________________                                                  Example                                                                              Comparative Comparative                                                IV-1   Example IV-1                                                                              Example IV-2                                     ______________________________________                                        Electrostatic                                                                 Characteristics*.sup.1)                                                       V.sub.10 (-V)                                                                 I (20° C., 65% RH)                                                                 690      670         675                                          II (30° C., 80% RH)                                                                680      655         665                                          D.R.R. (90 sec                                                                value) (%)                                                                    I (20° C., 65% RH)                                                                 88       85          87                                           II (30° C., 80% RH)                                                                84       83          83                                           E.sub.1/10  (erg/cm.sup.2)                                                    I (20° C., 65% RH)                                                                 18       24          22                                           II (30° C., 80% RH)                                                                22       28          25                                           E.sub.1/100  (erg/cm.sup.2)                                                   I (20° C., 65% RH)                                                                 28       39          35                                           II (30° C., 80% RH)                                                                34       45          40                                           Image Forming                                                                 Performance*.sup.25                                                           I (20° C., 65% RH)                                                                 Very     Scratches of                                                                              Scratches of                                             good     fine lines and                                                                            fine lines and                                                    letters,    letters,                                                          unevenness in                                                                             unevenness in                                                     half tone area                                                                            half tone area                               II (30° C., 80% RH)                                                                Very     Scratches of                                                                              Scratches of                                             good     fine lines and                                                                            fine lines and                                                    letters,    letters,                                                          unevenness in                                                                             unevenness in                                                     half tone area                                                                            half tone area                               ______________________________________                                    

The evaluation of each item shown in Table IV-1 was conducted in thefollowing manner.

*1) Electrostatic Characteristics

The light-sensitive material was charged with a corona discharge to avoltage of -6 kV for 20 seconds in a dark room using a paper analyzer("Paper Analyzer SP-428" manufactured by Kawaguchi Denki K.K.). Tenseconds after the corona discharge, the surface potential V₁₀ wasmeasured. The sample was then allowed to stand in the dark for anadditional 90 seconds, and the potential V₁₀₀ was measured. The darkdecay retention rate (DRR; %), i.e., percent retention of potentialafter dark decay for 90 seconds, was calculated from the followingequation:

    DRR(%)=(V.sub.100 /V.sub.10)×100

Separately, the surface of photoconductive layer was charged to -400 Vwith a corona discharge and then exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm), and the time required for decay of the surface potential V₁₀ toone-tenth was measured, and the exposure amount E_(1/10) (erg/cm²) wascalculated therefrom. Further, in the same manner as described above thetime required for decay of the surface potential V₁₀ to one-hundredthwas measured, and the exposure amount E_(1/100) (erg/cm²) was calculatedtherefrom. The measurements were conducted under ambient condition of20° C. and 65% RH (I) or 30° C. and 80% RH (II).

*2) Image Forming Performance

After the light-sensitive material was allowed to stand for one dayunder the ambient condition shown below, the light-sensitive materialwas charged to -6 kV and exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm; output: 2.8 mW) at an exposure amount of 64 erg/cm² (on thesurface of the photoconductive layer) at a pitch of 25 μm and a scanningspeed of 300 m/sec. The thus formed electrostatic latent image wasdeveloped with a liquid developer ("ELP-T" produced by Fuji Photo FilmCo., Ltd.), washed with a rinse solution of isoparaffinic solvent("Isopar G" manufactured by Esso Chemical K.K.) and fixed. Theduplicated image obtained was visually evaluated for fog and imagequality. The ambient condition at the time of image formation was 20° C.and 65% RH (I) or 30° C. and 80% RH (II).

As can be seen from the results shown in Table IV-1, the light-sensitivematerial according to the present invention had good electrostaticcharacteristics. The duplicated image obtained thereon was clear andfree from background fog. On the contrary, with the light-sensitivematerials of Comparative Examples IV-1 and IV-2 the decrease inphotosensitivity (E_(1/10) and E_(1/100)) occurred, and in theduplicated images the scratches of fine lines and letters were observedand a slight background fog remained without removing after the rinsetreatment. Further, the occurrence of unevenness in half tone areas ofcontinuous gradation of the original was observed regardless of theelectrostatic characteristics.

The value of E_(1/100) is largely different between the light-sensitivematerial of the present invention and those of the comparative examples.The value of E_(1/100) indicates an electrical potential remaining inthe non-image areas after exposure at the practice of image formation.The smaller this value, the less the background fog in the non-imageareas.

More specifically, it is required that the remaining potential isdecreased to -10 V or less. Therefore, an amount of exposure necessaryto make the remaining potential below -10 V is an important factor. Inthe scanning exposure system using a semiconductor laser beam, it isquite important to make the remaining potential below -10 V by a smallexposure amount in view of a design for an optical system of aduplicator (such as cost of the device, and accuracy of the opticalsystem).

From all these considerations, it is thus clear that anelectrophotographic light-sensitive material satisfying both therequirements of electrostatic characteristics and image formingperformance and being advantageously employed particularly in a scanningexposure system using a semiconductor laser beam can be obtained onlywhen the binder resin according to the present invention is used.

EXAMPLE IV-2

A mixture of 5 g (solid basis) of Resin (A-8), 35 g (solid basis) ofResin (B-102), 200 g of photoconductive zinc oxide, 0.020 g of MethineDye (IV-II) shown below, 0.20 g of N-hydroxymaleinimide and 300 g oftoluene was treated in the same manner as described in Example IV-1 toprepare an electrophotographic light-sensitive material. ##STR450##

With the light-sensitive material thus-prepared, a film property interms of surface smoothness, electrostatic characteristics and imageforming performance were evaluated. Further, printing property wasevaluated when it was used as an electrophotographic lithographicprinting plate precursor. The results obtained are shown in Table IV-2below.

                  TABLE IV-2                                                      ______________________________________                                                              Example IV-2                                            ______________________________________                                        Smoothness of Photoconductive Layer*.sup.3)                                                           465                                                   (sec/cc)                                                                      Electrostatic Characteristics                                                 V.sub.10 (-V)                                                                 I (20° C., 65% RH)                                                                             690                                                   II (30° C., 80% RH)                                                                            680                                                   D.R.R.                                                                        (90 sec value) (%)                                                            I (20° C., 65% RH)                                                                             89                                                    II (30° C., 80% RH)                                                                            86                                                    E.sub.1/10 (erg/cm.sup.2)                                                     I (20° C., 65% RH)                                                                             17                                                    II (30° C., 80% RH)                                                                            20                                                    E.sub.1/100 (erg/cm.sup.2)                                                    I (20° C., 65% RH)                                                                             26                                                    II (30° C., 80% RH)                                                                            35                                                    Image Forming Performance                                                     I (20° C., 65% RH)                                                                             Very good                                             II (30° C., 80% RH)                                                                            Very good                                             Contact Angle with Water*.sup.4) (°)                                                           10 or less                                            Printing Durability*.sup.5)                                                                           10,000 prints                                         ______________________________________                                    

The evaluation of each item shown in Table IV-2 was conducted in thefollowing manner.

*3) Smoothness of Photoconductive Layer

The smoothness (sec/cc) of the light-sensitive material was measuredusing a Beck's smoothness test machine (manufactured by Kumagaya RikoK.K.) under an air volume condition of 1 cc.

*4) Contact Angle with Water

The light-sensitive material was passed once through an etchingprocessor using a solution prepared by diluting an oil-desensitizingsolution ("ELP-EX" produced by Fuji Photo Film Co., Ltd.) to a two-foldvolume with distilled water to conduct oil-desensitization treatment onthe surface of the photoconductive layer. On the thus oil-desensitizedsurface was placed a drop of 2 μl of distilled water, and the contactangle formed between the surface and water was measured using agoniometer.

*5) Printing Durability

The light-sensitive material was subjected to plate making in the samemanner as described in *2) above to form toner images, and the surfaceof the photoconductive layer was subjected to oil-desensitizationtreatment under the same condition as in *4) above. The resultinglithographic printing plate was mounted on an offset printing machine("Oliver Model 52", manufactured by Sakurai Seisakusho K.K.), andprinting was carried out on paper. The number of prints obtained untilbackground stains in the non-image areas appeared or the quality of theimage areas was deteriorated was taken as the printing durability. Thelarger the number of the prints, the higher the printing durability.

As can be seen from the results shown in Table IV-2, the light-sensitivematerial according to the present invention had good surface smoothness,film strength and electrostatic characteristics of the photoconductivelayer. The duplicated image obtained was clear and free from backgroundfog in the non-image area. These results appear to be due to sufficientadsorption of the binder resin onto the photoconductive substance andsufficient covering of the surface of the particles with the binderresin. For the same reason, when it was used as an offset master plateprecursor, oil-desensitization of the offset master plate precursor withan oil-desensitizing solution was sufficient to render the non-imageareas satisfactorily hydrophilic, as shown by a small contact angle of10° or less with water. On practical printing using the resulting masterplate, 10,000 prints of clear image without background stains wereobtained.

From these results it is believed that the resin (A) and the resin (B)according to the present invention suitably interacts with zinc oxideparticles to form the condition under which an oil-desensitizingreaction proceeds easily and sufficiently with an oil-desensitizingsolution and that the remarkable improvement in film strength isachieved by the action of the resin (B).

EXAMPLES IV-3 TO IV-18

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example IV-2, except for using each ofResins (A) and Resins (B) shown in Table IV-3 below in place of Resin(A-8) and Resin (B-102) used in Example IV-2, respectively.

The electrostatic characteristics of the resulting light-sensitivematerials were evaluated in the same manner as described in ExampleIV-2. The results obtained are shown in Table IV-3 below.

                  TABLE IV-3                                                      ______________________________________                                                                                   E.sub.1/100                               Resin   Resin   V.sub.10                                                                            D.R.R.                                                                              E.sub.1/10                                                                            (erg/                              Example                                                                              (A)     (B)     (-V)  (%)   (erg/cm.sup.2)                                                                        cm.sup.2)                          ______________________________________                                        IV-3   A-1     B-103   630   80    25      35                                 IV-4   A-3     B-105   655   82    22      36                                 IV-5   A-4     B-106   585   80    25      36                                 IV-6   A-6     B-107   590   81    23      35                                 IV-7   A-10    B-108   650   83    23      34                                 IV-8   A-12    B-110   580   82    25      36                                 IV-9   A-13    B-112   585   80    26      37                                 IV-10  A-6     B-113   575   81    25      35                                 IV-11  A-7     B-114   615   82    26      36                                 IV-12  A-8     B-115   625   83    25      35                                 IV-13  A-22    B-117   575   80    26      38                                 IV-14  A-23    B-119   635   81    24      36                                 IV-15  A-24    B-121   590   80    26      34                                 IV-16  A-27    B-123   585   79    27      36                                 IV-17  A-28    B-126   575   79    26      35                                 IV-18  A-29    B-131   685   82    23      33                                 ______________________________________                                    

The electrostatic characteristics were evaluated under condition of 30°C. and 80% RH.

As shown in Table IV-3, the light-sensitive materials according to thepresent invention were excellent in charging properties, dark chargeretention rate and photosensitivity. Also, as a result of the evaluationon image forming performance of each light-sensitive material, it wasfound that clear duplicated images having good reproducibility of finelines and letters and no occurrence of unevenness in half tone areaswithout the formation of background fog were obtained. Further, whenthese electrophotographic light-sensitive materials were employed asoffset master plate precursors under the same printing condition asdescribed in Example IV-2, more than 10,000 good prints were obtainedrespectively.

EXAMPLES IV-19 TO IV-22

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example IV-1, except for using each of thedye shown in Table IV-4 below in place of Cyanine Dye (IV-1) used inExample IV-1.

                                      TABLE IV-4                                  __________________________________________________________________________    Example                                                                            Dye  Chemical Structure of Dye                                           __________________________________________________________________________    IV-19                                                                              (IV-III)                                                                            ##STR451##                                                         IV-20                                                                              (IV-IV)                                                                             ##STR452##                                                         IV-21                                                                              (IV-V)                                                                              ##STR453##                                                         IV-22                                                                              (IV-VI)                                                                             ##STR454##                                                         __________________________________________________________________________

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided clear duplicated images free frombackground fog even when processed under severe condition of hightemperature and high humidity (30° C. and 80% RH).

EXAMPLES IV-23 AND IV-24

A mixture of 6.5 g of Resin (A-1) (Example IV-23) or Resin (A-7)(Example IV-24), 33.5 g of Resin (B-108), 200 g of zinc oxide, 0.02 g ofuranine, 0.03 g of Methine Dye (IV-VII) shown below, 0.03 g of MethineDye (IV-VIII) shown below, 0.18 g of p-hydroxybenzoic acid and 300 g oftoluene was dispersed by a homogenizer at 7×10³ r.p.m. for 10 minutes toprepare a coating composition for a light-sensitive layer. The coatingcomposition was coated on paper, which had been subjected toelectrically conductive treatment, by a wire bar at a dry coverage of 20g/m², and dried for 20 seconds at 110° C. Then, the coated material wasallowed to stand in a dark place for 24 hours under the conditions of20° C. and 65% RH to prepare each electrophotographic light-sensitivematerial. ##STR455##

COMPARATIVE EXAMPLE IV-3

An electrophotographic light-sensitive material was prepared in the samemanner as in Example IV-23, except for using Resin (R-IV-3) shown belowin place of Resin (B-108) used in Example IV-23. ##STR456##

With each of the light-sensitive materials thus prepared, variouscharacteristics were evaluated in the same manner as in Example IV-2.The results obtained are shown in Table IV-5 below.

                                      TABLE IV-5                                  __________________________________________________________________________                    Example IV-23                                                                         Example IV-24                                                                         Comparative Example IV-3                      __________________________________________________________________________    Binder Resin    (A-1)/(B-108)                                                                         (A-7)/(B-108)                                                                         (A-1)/(R-IV-3)                                Smoothness of Photoconductive                                                                 500     505     500                                           Layer (sec/cc)                                                                Electrostatic Characteristics*.sup.6)                                         V.sub.10 (-V)                                                                 I (20° C., 65% RH)                                                                     590     685     585                                           II (30° C., 80% RH)                                                                    580     670     570                                           D.R.R. (%)                                                                    I (20° C., 65% RH)                                                                     92      97      90                                            II (30° C., 80% RH)                                                                    88      94      85                                            E.sub.1/10 (lux · sec)                                               I (20° C., 65% RH)                                                                     9.5     8.3     11.8                                          II (30° C., 80% RH)                                                                    10.2    9.4     12.6                                          E.sub.1/100 (lux · sec)                                              I (20° C., 65% RH)                                                                     15      13      19                                            II (30° C., 80% RH)                                                                    16      15      20                                            Image Forming*.sup.7)                                                         Performance                                                                   I (20° C., 65% RH)                                                                     Good    Very good                                                                             Edge mark of cutting                          II (30° C., 80% RH)                                                                    Good    Very good                                                                             Edge mark of cutting,                                                         unevenness in half                                                            tone area                                     Contact Angle with Water (°)                                                           10 or less                                                                            10 or less                                                                            10 or less                                    Printing Durability                                                                           10,000  10,000  Background stain due to                                       prints  prints  edge mark of cutting                                                          occurred from the start                                                       of printing                                   __________________________________________________________________________

The characteristics were evaluated in the same manner as in ExampleIV-2, except that some electrostatic characteristics and image formingperformance were evaluated according to the following test methods.

*6) Measurement of Electrostatic Characteristics: E_(1/10) and E_(1/10)0

The surface of the photoconductive layer was charged to -400 V withcorona discharge, and then irradiated by visible light of theilluminance of 2.0 lux. Then, the time required for decay of the surfacepotential (V₁₀) to 1/10 or 1/100 thereof was determined, and theexposure amount E_(1/10) or E_(1/100) (lux·sec) was calculatedtherefrom.

*7) Image Forming Performance

The electrophotographic light-sensitive material was allowed to standfor one day under the ambient condition described below, thelight-sensitive material was subjected to plate making by afull-automatic plate making machine (ELP-404V manufactured by Fuji PhotoFilm Co., Ltd.) using ELP-T as a toner. The duplicated image thusobtained was visually evaluated for fog and image quality. The ambientcondition at the time of image formation was 20° C. and 65% RH (I) or30° C. and 80% RH (II). The original used for the duplication wascomposed of cuttings of other originals pasted up thereon.

From the results shown above, it can be seen that each light-sensitivematerial exhibited almost the same properties with respect to thesurface smoothness and mechanical strength of the photoconductive layer.However, on the electrostatic characteristics, the light-sensitivematerial of Comparative Example IV-3 had the particularly large value ofphotosensitivity E_(1/100), and this tendency increased under the hightemperature and high humidity condition. On the contrary, theelectrostatic characteristics of the light-sensitive material accordingto the present invention were good. Further, those of Example IV-24using the resin (A') were very good. The value of E_(1/100) thereof wasparticularly small.

With respect to image forming performance, the edge mark of cuttingspasted up was observed as background fog in the non-image areas in thelight-sensitive material of Comparative Example IV-3. On the contrary,the light-sensitive materials according to the present inventionprovided clear duplicated images free from background fog.

Further, each of these light-sensitive materials was subjected to theoil-desensitizing treatment to prepare an offset printing plate andusing the resulting plate printing was conducted. The plates accordingto the present invention provided 10,000 prints of clear image withoutbackground stains. However, with the plate of Comparative Example IV-3,the above described edge mark of cuttings pasted up was not removed withthe oil-desensitizing treatment and the background stains occurred fromthe start of printing.

It can be seen from the results described above that the light-sensitivematerials according to the present invention were excellent in allaspects of the surface smoothness and mechanical strength of thephotoconductive layer, electrostatic characteristics and printingproperty. Further, it can be seen that the electrostatic characteristicsare more improved by using the resin (A').

EXAMPLE IV-25

A mixture of 5 g of Resin (A-29), 35 g of Resin (B-127), 200 g of zincoxide, 0.02 g of uranine, 0.04 g of Rose Bengal, 0.03 g of bromophenolblue, 0.40 g of phthalic anhydride and 300 g of toluene was treated inthe same manner as described in Example IV-23 to prepare anelectrophotographic light-sensitive material.

As the result of the evaluation of various characteristics in the samemanner as described in Example IV-23, it can be seen that thelight-sensitive material according to the present invention is excellentin charging properties, dark charge retention rate and photosensitivity,and provides a clear duplicated image free from background fog undersevere conditions of high temperature and high humidity (30° C. and 80%RH). Further, when the material was employed as an offset master plateprecursor, 10,000 prints of clear image were obtained.

EXAMPLES IV-26 TO IV-37

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example IV-25, except for using 6 g of eachof Resin (A) and 34 g of each of Resin (B) shown in Table IV-6 below inplace of 5 g of Resin (A-29) and 35 g of Resin (B127) used in ExampleIV-25, respectively.

                  TABLE IV-6                                                      ______________________________________                                        Example        Resin (A)    Resin (B)                                         ______________________________________                                        IV-26          A-2          B-103                                             IV-27          A-4          B-107                                             IV-28          A-5          B-110                                             IV-29          A-10         B-116                                             IV-30          A-11         B-120                                             IV-31          A-15         B-122                                             IV-32          A-20         B-126                                             IV-33          A-21         B-127                                             IV-34          A-22         B-128                                             IV-35          A-25         B-129                                             IV-36          A-26         B-132                                             IV-37          A-28         B-133                                             ______________________________________                                    

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided a clear duplicated image free frombackground fog and scratches of fine lines even under severe conditionof high temperature and high humidity (30° C. and 80% RH). Further, whenthese materials were employed as offset master plate precursors, 10,000prints of a clear image free from background stains were obtainedrespectively.

EXAMPLE V-1

A mixture of 8 g (solid basis) of Resin (A-104), 32 g (solid basis) ofResin (B-101), 200 g of photoconductive zinc oxide, 0.018 g of CyanineDye (V-I) having the following structure, 0.15 g of salicylic acid and300 g of toluene was dispersed by a homogenizer (manufactured by NipponSeiki K.K.) at a rotation of 7×10³ r.p.m. for 10 minutes to prepare acoating composition for a light-sensitive layer. The coating compositionwas coated on paper, which had been subjected to electrically conductivetreatment, by a wire bar at a dry coverage of 25 g/m², followed bydrying at 110° C. for 10 seconds. The coated material was then allowedto stand in a dark place at 20° C. and 65% RH for 24 hours to prepare anelectrophotographic light-sensitive material. ##STR457##

COMPARATIVE EXAMPLE V-1

An electrophotographic light-sensitive material was prepared in the samemanner as in Example V-1, except for using 32 g of Resin (R-V-1) havingthe following structure in place of 32 g of Resin (B-101) used inExample V-1. ##STR458##

COMPARATIVE EXAMPLE V-2

An electrophotographic light-sensitive material was prepared in the samemanner as in Example V-1, except for using 32 g of Resin (R-V-2) havingthe following structure in place of 32 g of Resin (B-101) used inExample V-1. ##STR459##

With each of the light-sensitive materials thus prepared, electrostaticcharacteristics and image forming performance were evaluated. Theresults obtained are shown in Table V-1 below.

                  TABLE V-1                                                       ______________________________________                                                   Example                                                                              Comparative Comparative                                                V-1    Example V-1 Example V-2                                     ______________________________________                                        Electrostatic*.sup.1)                                                         Characteristics                                                               V.sub.10 (-V)                                                                 I (20° C., 65% RH)                                                                  780      730         770                                         II (30° C., 80% RH)                                                                 760      715         750                                         III (15° C., 30% RH)                                                                805      740         775                                         D.R.R. (90 sec                                                                value) (%)                                                                    I (20° C., 65% RH)                                                                  87       87          87                                          II (30° C., 80% RH)                                                                 84       81          83                                          III (15° C., 30% RH)                                                                88       89          87                                          E.sub.1/10 (erg/cm.sup.2)                                                     I (20° C., 65% RH)                                                                  15       18          18                                          II (30° C., 80% RH)                                                                 16       21          20                                          III (15° C., 30% RH)                                                                19       25          27                                          E.sub.1/100 (erg/cm.sup.2)                                                    I (20° C., 65% RH)                                                                  23       29          30                                          II (30° C., 80% RH)                                                                 25       34          35                                          III (15° C., 30% RH)                                                                30       45          47                                          Image Forming*.sup.2)                                                         Performance                                                                   I (20° C., 65% RH)                                                                  Good     Good        Good                                        II (30° C., 80% RH)                                                                 Good     Unevenness  Unevenness                                                        in image    in image                                                          portion     portion                                     III (15° C., 30% RH)                                                                Good     Unevenness  Unevenness                                                        in image por-                                                                             in image por-                                                     tion, slight                                                                              tion, slight                                                      background fog                                                                            background                                                                    fog                                         ______________________________________                                    

The evaluation of each item shown in Table V-1 was conducted in thefollowing manner.

*1) Electrostatic Characteristics

The light-sensitive material was charged with a corona discharge to avoltage of -6 kV for 20 seconds in a dark room using a paper analyzer("Paper Analyzer SP-428" manufactured by Kawaguchi Denki K.K.). Tenseconds after the corona discharge, the surface potential V₁₀ wasmeasured. The sample was then allowed to stand in the dark for anadditional 90 seconds, and the potential V₁₀₀ was measured. The darkcharge retention rate (DRR; %), i.e., percent retention of potentialafter dark decay for 90 seconds, was calculated from the followingequation:

    DRR(%)=(V.sub.100 /V.sub.10)×100

Separately, the surface of photoconductive layer was charged to -400 Vwith a corona discharge and then exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm), and the time required for decay of the surface potential V₁₀ toone-tenth was measured, and the exposure amount E_(1/10) (erg/cm²) wascalculated therefrom. Further, in the same manner as described above thetime required for decay of the surface potential V₁₀ to one-hundredthwas measured, and the exposure amount E_(1/100) (erg/cm²) was calculatedtherefrom. The measurements were conducted under ambient condition of20° C. and 65% RH (I), 30° C. and 80% RH (II) or 15° C. and 30% RH(III).

*2) Image Forming Performance

After the light-sensitive material was allowed to stand for one dayunder the ambient condition shown below, the light-sensitive materialwas charged to -6 kV and exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm; output: 2.8 mW) at an exposure amount of 64 erg/cm² (on thesurface of the photoconductive layer) at a pitch of 25 μm and a scanningspeed of 300 m/sec. The thus formed electrostatic latent image wasdeveloped with a liquid developer ("ELP-T" produced by Fuji Photo FilmCo., Ltd.), washed with a rinse solution of isoparaffinic solvent("Isopar G" manufactured by Esso Chemical K.K.) and fixed. Theduplicated image obtained was visually evaluated for fog and imagequality. The ambient condition at the time of image formation was 20° C.and 65% RH (I), 30° C. and 80% RH (II) or 15° C. and 30% RH (III).

As can be seen from the results shown in Table V-1, the light-sensitivematerial according to the present invention exhibited good electrostaticcharacteristics and provided duplicated image which was clear and freefrom background fog, even when the ambient condition was fluctuated. Onthe contrary, with the light-sensitive materials of Comparative ExamplesV-1 and V-2 the decrease in photosensitivity (E_(1/10) and E_(1/100))occurred, and in the duplicated images the scratches of fine lines andletters were observed and a slight background fog remained withoutremoving after the rinse treatment. Further, the occurrence ofunevenness in half tone areas of continuous gradation of the originalwas observed under the ambient condition II, and the occurrence of smallwhite spots in the image portion was observed under the ambientcondition III regardless of the electrostatic characteristics.

The value of E_(1/100) is largely different between the light-sensitivematerial of the present invention and those of the comparative examples.The value of E_(1/100) indicates an electrical potential remaining inthe non-image areas after exposure at the practice of image formation.The smaller this value, the less the background fog in the non-imageareas. More specifically, it is required that the remaining potential isdecreased to -10 V or less. Therefore, an amount of exposure necessaryto make the remaining potential below -10 V is an important factor. Inthe scanning exposure system using a semiconductor laser beam, it isquite important to make the remaining potential below -10 V by a smallexposure amount in view of a design for an optical system of aduplicator (such as cost of the device, and accuracy of the opticalsystem).

From all these considerations, it is thus clear that anelectrophotographic light-sensitive material satisfying bothrequirements of electrostatic characteristics and image formingperformance and being advantageously employed particularly in a scanningexposure system using a semiconductor laser beam can be obtained onlywhen the binder resin according to the present invention is used.

EXAMPLE V-2

A mixture of 6 g (solid basis) of Resin (A-119), 34 g (solid basis) ofResin (B-102), 200 g of photoconductive zinc oxide, 0.020 g of MethineDye (V-II) having the following formula, 0.23 g of N-hydroxymaleinimideand 300 g of toluene was treated in the same manner as described inExample V-1 to prepare an electrophotographic light-sensitive material.##STR460##

COMPARATIVE EXAMPLE V-3

An electrophotographic light-sensitive material was prepared in the samemanner as in Example V-2, except for using 34 g of Resin (R-V-3) havingthe following structure in place of 34 g of Resin (B-102) used inExample V-2. ##STR461##

COMPARATIVE EXAMPLE V-4

An electrophotographic light-sensitive material was prepared in the samemanner as in Example V-2, except for using 34 g of Resin (R-V-4) havingthe following structure in place of 34 g of Resin (B-102) used inExample V-2. ##STR462##

With each of the light-sensitive materials thus-prepared, a filmproperty in terms of surface smoothness, mechanical strength,electrostatic characteristics and image forming performance wereevaluated. Further, printing property was evaluated when it was used asan electrophotographic lithographic printing plate precursor. Theresults obtained are shown in Table V-2 below.

                                      TABLE V-2                                   __________________________________________________________________________                             Comparative                                                                           Comparative                                                   Example V-2                                                                           Example V-3                                                                           Example V-4                                  __________________________________________________________________________    Smoothness of Photoconductive*.sup.3)                                                          430     435     425                                          Layer (sec/cc)                                                                Mechanical Strength of*.sup.4)                                                                 91      74      83                                           Photoconductive Layer (%)                                                     Electrostatic Characteristics                                                 V.sub.10 (-V)                                                                 I (20° C., 65% RH)                                                                      780     725     735                                          II (30° C., 80% RH)                                                                     750     690     705                                          III (15° C., 30% RH)                                                                    790     730     740                                          D.R.R. (%)                                                                    (90 sec value)                                                                I (20° C., 65% RH)                                                                      88      80      84                                           II (30° C., 80% RH)                                                                     83      72      79                                           III (15° C., 30% RH)                                                                    87      80      83                                           E.sub.1/10  (erg/cm.sup.2)                                                    I (20° C., 65% RH)                                                                      19      30      25                                           II (30° C., 80% RH)                                                                     23      25      23                                           III (15° C., 30% RH)                                                                    30      39      30                                           Image Forming                                                                 Performance                                                                   I (20° C., 65% RH)                                                                      Good    Good    Good                                         II (30° C., 80% RH)                                                                     Good    Unevenness in                                                                         Slight unevenness                                                     half tone area                                                                        in half tone area                            III(15° C., 30% RH)                                                                     Good    Unevenness in                                                                         Unevenness in                                                         half tone area,                                                                       half tone area,                                                       unevenness of                                                                         unevenness of                                                         white spots in                                                                        white spots in                                                        image portion                                                                         image portion                                Water Retentivity of*.sup.5)                                                                   No background                                                                         Background                                                                            Slight background                            Light-Sensitive Material                                                                       stain at all                                                                          stain   stain                                        Printing Durability*.sup.6)                                                                    10,000 prints                                                                         4,500 prints                                                                          6,000 prints                                 __________________________________________________________________________

The evaluation of each item shown in Table V-2 was conducted in thefollowing manner.

*3) Smoothness of Photoconductive Layer

The smoothness (sec/cc) of the light-sensitive material was measuredusing a Beck's smoothness test machine (manufactured by Kumagaya RikoK.K.) under an air volume condition of 1 cc.

*4) Mechanical Strength of Photoconductive Layer

The surface of the light-sensitive material was repeatedly (1000 times)rubbed with emery paper (#1000) under a load of 75 g/cm² using a Heidon14 Model surface testing machine (manufactured by Shinto Kagaku K.K.).After dusting, the abrasion loss of the photoconductive layer wasmeasured to obtain film retention (%).

*5) Water Retentivity of Light-Sensitive Material

A light-sensitive material without subjecting to plate making was passedtwice through an etching processor using an aqueous solution obtained bydiluting an oil-desensitizing solution ("ELP-EX" produced by Fuji PhotoFilm Co., Ltd.) to a five-fold volume with distilled water to conduct anoil-desensitizing treatment of the surface of the photoconductive layer.The material thus-treated was mounted on an offset printing machine("611XLA-II Model" manufactured by Hamada Printing Machine ManufacturingCo.) and printing was conducted using distilled water as dampeningwater. The extent of background stain occurred on the 50th print wasvisually evaluated. This testing method corresponds to evaluation ofwater retentivity after oil-desensitizing treatment of thelight-sensitive material under the forced condition.

*6) Printing Durability

The light-sensitive material was subjected to plate making in the samemanner as described in *2) above to form toner images, and the surfaceof the photoconductive layer was subjected to oil-desensitizationtreatment by passing twice through an etching processor using ELP-EX.The resulting lithographic printing plate was mounted on an offsetprinting machine ("Oliver Model 52", manufactured by Sakurai SeisakushoK.K.), and printing was carried out on paper. The number of printsobtained until background stains in the non-image areas appeared or thequality of the image areas was deteriorated was taken as the printingdurability. The larger the number of the prints, the higher the printingdurability.

As can be seen from the results shown in Table V-2, the light-sensitivematerial according to the present invention had good surface smoothness,film strength and electrostatic characteristics of the photoconductivelayer. The duplicated image obtained was clear and free from backgroundfog. These results appear to be due to sufficient adsorption of thebinder resin onto the photoconductive substance and sufficient coveringof the surface of the particles with the binder resin. For the samereason, when it was used as an offset master plate precursor,oil-desensitization of the offset master plate precursor with anoil-desensitizing solution was sufficient to render the non-image areassatisfactorily hydrophilic and adhesion of ink was not observed at allas a result of the evaluation of water retentivity under the forcedcondition. On practical printing using the resulting master plate,10,000 prints of clear image without background stains were obtained.

On the contrary, with the light-sensitive materials of ComparativeExamples V-3 and V-4, the occurrence of slight background stain innon-image area, unevenness in highly accurate image of continuousgradation and unevenness of white spots in image portion was observedwhen the image formation was conducted under severe conditions. Further,as a result of the test on water retentivity of these light-sensitivematerials to make offset master plates, the adhesion of ink wasobserved. The printing durability thereof was at most from 4,000 to6,000 prints.

From these results it is believed that the resin (A) and the resin (B)according to the present invention suitably interacts with zinc oxideparticles to form the condition under which an oil-desensitizingreaction proceeds easily and sufficiently with an oil-desensitizingsolution and that the remarkable improvement in film strength isachieved by the action of the resin (B).

EXAMPLES V-3 TO V-22

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example V-2, except for using each of Resins(A) and Resins (B) shown in Table V-3 below in place of Resin (A-119)and Resin (B-102) used in Example V-2, respectively.

                  TABLE V-3                                                       ______________________________________                                        Example        Resin (A)    Resin (B)                                         ______________________________________                                        V-3            A-101        B-103                                             V-4            A-103        B-104                                             V-5            A-105        B-101                                             V-6            A-106        B-105                                             V-7            A-111        B-106                                             v-8            A-112        B-107                                             V-9            A-116        B-108                                             V-10           A-118        B-109                                             V-11           A-119        B-111                                             V-12           A-120        B-112                                             V-13           A-121        B-113                                             V-14           A-122        B-115                                             V-15           A-123        B-116                                             V-16           A-124        B-120                                             V-17           A-128        B-121                                             V-18           A-129        B-123                                             V-19           A-131        B-124                                             V-20           A-133        B-130                                             V-21           A-104        B-131                                             V-22           A-110        B-133                                             ______________________________________                                    

The electrostatic characteristics and image forming performance of eachof the light-sensitive materials were determined in the same manner asdescribed in Example V-1. Each light-sensitive material exhibited goodelectrostatic characteristics. As a result of the evaluation on imageforming performance of each light-sensitive material, it was found thatclear duplicated images having good reproducibility of fine lines andletters and no occurrence of unevenness in half tone areas without theformation of background fog were obtained.

Further, when these electrophotographic light-sensitive materials wereemployed as offset master plate precursors under the same printingcondition as described in Example V-2, more than 10,000 good prints wereobtained respectively.

It can be seen from the results described above that each of thelight-sensitive materials according to the present invention wassatisfactory in all aspects of the surface smoothness and film strengthof the photoconductive layer, electrostatic characteristics and printingproperty.

EXAMPLES V-23 TO V-26

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example V-1, except for using each of thedyes shown in Table V-4 below in place of Cyanine Dye (V-1) used inExample V-1.

                                      TABLE V-4                                   __________________________________________________________________________    Example                                                                            Dye  Chemical Structure of Dye                                           __________________________________________________________________________    V-23 (V-III)                                                                             ##STR463##                                                         V-24 (V-IV)                                                                              ##STR464##                                                         V-25 (V-V)                                                                               ##STR465##                                                         V-26 (V-VI)                                                                              ##STR466##                                                         __________________________________________________________________________

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided clear duplicated images free frombackground fog even when processed under severe conditions of hightemperature and high humidity (30° C. and 80% RH) and low temperatureand low humidity (15° C. and 30% RH).

EXAMPLES V-27 AND V-28

A mixture of 6.5 g of Resin (A-101) (Example V-27) or Resin (A-128)(Example V-28), 33.5 g of Resin (B-118), 200 g of photoconductive zincoxide, 0.02 g of uranine, 0.03 g of Methine Dye (V-VII) having thefollowing structure, 0.03 g of Methine Dye (V-VIII) having the followingstructure, 0.18 g of phthalic anhydride and 300 g of toluene wasdispersed by a homogenizer at a rotation of 7×10³ r.p.m. for 8 minutesto prepare a coating composition for a light-sensitive layer. Thecoating composition was coated on paper, which had been subjected toelectrically conductive treatment, by a wire bar at a dry coverage of 20g/m², and dried for 20 seconds at 110° C. Then, the coated material wasallowed to stand in a dark place for 24 hours under the conditions of20° C. and 65% RH to prepare each electrophotographic light-sensitivematerial. ##STR467##

COMPARATIVE EXAMPLE V-5

An electrophotographic light-sensitive material was prepared in the samemanner as in Example V-27, except for using 33.5 g of Resin (R-V-5)having the following structure in place of 33.5 g of Resin (B-118) usedin Example V-27. ##STR468##

With each of the light-sensitive materials thus prepared, variouscharacteristics were evaluated in the same manner as in Example V-2. Theresults obtained are shown in Table V-5 below.

                                      TABLE V-5                                   __________________________________________________________________________                    Example V-27                                                                          Example V-28                                                                          Comparative Example V-5                       __________________________________________________________________________    Binder Resin    (A-101)/(B-118)                                                                       (A-128)/(B-118)                                                                       (A-101)/(R-V-5)                               Smoothness of Photoconductive                                                                 405     400     400                                           Layer (sec/cc)                                                                Mechanical Strength of                                                                        90      92      75                                            Photoconductive Layer (%)                                                     Electrostatic characteristics*.sup.7)                                         V.sub.10 (-V)                                                                 I (20° C., 65% RH)                                                                     660     750     610                                           II (30° C., 80% RH)                                                                    645     735     590                                           III (15° C., 30% RH)                                                                   670     765     615                                           D.R.R. (%)                                                                    I (20° C., 65% RH)                                                                     90      97      88                                            II (30° C., 80% RH)                                                                    87      91      80                                            III (15° C., 30% RH)                                                                   91      97      87                                            E.sub.1/10  (lux · sec)                                              I (20° C., 65% RH)                                                                     10.3    8.9     14.0                                          II (30° C., 80% RH)                                                                    9.6     8.5     13.2                                          III (15° C., 30% RH)                                                                   11.2    9.8     15.6                                          Image Forming*.sup.8)                                                         Performance                                                                   I (20° C., 65% RH)                                                                     Good    Very good                                                                             Good                                          II (30° C., 80% RH)                                                                    Good    Very good                                                                             Edge mark of cutting,                                                         unevenness in half                                                            tone area                                     III (15° C., 30% RH)                                                                   Good    Very good                                                                             Edge mark of cutting,                                                         unevenness in image                                                           portion                                       Water Retentivity of                                                                          Good    Good    Slight background stain                       Light-Sensitive Material                                                      Printing Durability                                                                           10,000  10,000  Background stain from                                         prints  prints  the start of printing                         __________________________________________________________________________

The characteristics were evaluated in the same manner as in Example V-2,except that some electrostatic characteristics and image formingperformance were evaluated according to the following test methods.

*7) Measurement of Electrostatic Characteristics: E_(1/10)

The surface of the photoconductive layer was charged to -400 V withcorona discharge, and then irradiated by visible light of theilluminance of 2.0 lux on the surface of the photoconductive layer.Then, the time required for decay of the surface potential (V₁₀) to 1/10thereof was determined, and the exposure amount E_(1/10) (lux·sec) wascalculated therefrom.

*8) Image Forming Performance

The electrophotographic light-sensitive material was allowed to standfor one day under the ambient condition described below, thelight-sensitive material was subjected to plate making by afull-automatic plate making machine (ELP-404V manufactured by Fuji PhotoFilm Co., Ltd.) using ELP-T as a toner. The duplicated image thusobtained was visually evaluated for fog and image quality. The ambientcondition at the time of image formation was 20° C. and 65% RH (I), 30°C. and 80% RH (II) or 15° C. and 30% RH (III). The original used for theduplication was composed of cuttings of other originals pasted upthereon.

From the results, it can be seen that each of the light-sensitivematerials according to the present invention exhibited good mechanicalstrength of the photoconductive layer. On the contrary, with thelight-sensitive material of Comparative Example V-5 the value ofmechanical strength was lower than them, and the value of E_(1/10) ofelectrostatic characteristics degraded particularly under the ambientcondition of low temperature and low humidity (III), while they weregood under the ambient condition of normal temperature and normalhumidity (I). On the other hand, the electrostatic characteristics ofthe light-sensitive materials according to the present invention weregood. Particularly, those of Example V-28 using the resin (A') were verygood. The value of E_(1/100) thereof was particularly small.

With respect to image forming performance, the edge mark of cuttingspasted up was observed as background fog in the non-image areas in thelight-sensitive material of Comparative Example V-5. Also the occurrenceof unevenness in half tone area of continuous gradation and unevennessof small white spots in image portion were observed on the duplicatedimage when the ambient conditions at the time of the image formationwere high temperature and high humidity (II) and low temperature and lowhumidity (III).

Further, each of these light-sensitive materials was subjected to theoil-desensitizing treatment to prepare an offset printing plate andusing the resulting plate printing was conducted. The plates accordingto the present invention provided 10,000 prints of clear image withoutbackground stains. However, with the plate of Comparative Example V-5,the above-described edge mark of cuttings pasted up was not removed withthe oil-desensitizing treatment and the background stains occurred fromthe start of printing.

It can be seen from the results described above that only thelight-sensitive materials according to the present invention couldprovide excellent performance.

EXAMPLE V-29

A mixture of 5 g of Resin (A-107), 35 g of Resin (B-108), 200 g ofphotoconductive zinc oxide, 0.02 g of uranine, 0.04 g of Rose Bengal,0.03 g of bromophenol blue, 0.40 g of phthalic anhydride and 300 g oftoluene was treated in the same manner as described in Example V-27 toprepare an electrophotographic light-sensitive material.

As the result of the evaluation of various characteristics in the samemanner as described in Example V-27, it can be seen that thelight-sensitive material according to the present invention is excellentin charging properties, dark charge retention rate and photosensitivity,and provides a clear duplicated image free from background fog undersevere conditions of high temperature and high humidity (30° C. and 80%RH) and low temperature and low humidity (15° C. and 30% RH). Further,when the material was employed as an offset master plate precursor,10,000 prints of clear image were obtained.

EXAMPLES V-30 TO V-53

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example V-29, except for using 5 g of eachof Resin (A) and 35 g of each of Resin (B) shown in Table V-6 below inplace of 5 g of Resin (A-107) and 35 g of Resin (B-108) used in ExampleV-29, respectively.

                  TABLE V-6                                                       ______________________________________                                        Example        Resin (A)    Resin (B)                                         ______________________________________                                        V-30           A-101        B-106                                             V-31           A-103        B-101                                             V-32           A-104        B-102                                             V-33           A-105        B-104                                             V-34           A-106        B-105                                             V-35           A-109        B-106                                             V-36           A-110        B-108                                             V-37           A-111        B-110                                             V-38           A-112        B-112                                             V-39           A-113        B-114                                             V-40           A-117        B-117                                             V-41           A-119        B-119                                             V-42           A-121        B-120                                             V-43           A-122        B-121                                             V-44           A-124        B-122                                             V-45           A-125        B-123                                             V-46           A-126        B-124                                             V-47           A-127        B-125                                             V-48           A-128        B-126                                             v-49           A-129        B-127                                             V-50           A-114        B-128                                             V-51           A-116        B-129                                             V-52           A-123        B-130                                             V-53           A-127        B-132                                             ______________________________________                                    

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided a clear duplicated image free frombackground fog and scratches of fine lines even under severe conditionsof high temperature and high humidity (30° C. and 80% RH) and lowtemperature and low humidity (15° C. and 30% RH). Further, when thesematerials were employed as offset master plate precursors, 10,000 printsof a clear image free from background stains were obtained respectively.

EXAMPLE VI-1

A mixture of 6 g (solid basis) of Resin (A-205), 34 g (solid basis) ofResin (B-101), 200 g of photoconductive zinc oxide, 0.018 g of CyanineDye (VI-I) shown below, 0.15 g of phthalic anhydride and 300 g oftoluene was dispersed by a homogenizer (manufactured by Nippon SeikiK.K.) at a rotation of 6×10³ r.p.m. for 10 minutes to prepare a coatingcomposition for a light-sensitive layer. The coating composition wascoated on paper, which had been subjected to electrically conductivetreatment, by a wire bar at a dry coverage of 22 g/m², followed bydrying at 110° C. for 10 seconds. The coated material was then allowedto stand in a dark place at 20° C. and 65% RH (relative humidity) for 24hours to prepare an electrophotographic light-sensitive material.##STR469##

COMPARATIVE EXAMPLE VI-1

An electrophotographic light-sensitive material was prepared in the samemanner as in Example VI-1, except for using 34 g of Resin (R-VI-1) shownbelow in place of 34 g of Resin (B-101) used in Example VI-1. ##STR470##

COMPARATIVE EXAMPLE VI-2

An electrophotographic light-sensitive material was prepared in the samemanner as in Example VI-1, except for using 34 g of Resin (R-VI-2) shownbelow in place of 34 g of Resin (B-101) used in Example VI-1. ##STR471##

With each of the light-sensitive material thus prepared, electrostaticcharacteristics and image forming performance were evaluated. Theresults obtained are shown in Table VI-1 below.

                  TABLE VI-1                                                      ______________________________________                                                                      Comparative                                                Example                                                                              Comparative Example                                                    VI-1   Example VI-1                                                                              VI-2                                            ______________________________________                                        Electrostatic*.sup.1)                                                         Characteristics                                                               V.sub.10 (-V)                                                                 I (20° C., 65% RH)                                                                  760      745         765                                         II (30° C., 80% RH)                                                                 745      710         745                                         III (15° C., 30% RH)                                                                755      750         765                                         D.R.R. (90 sec                                                                value) (%)                                                                    I (20° C., 65% RH)                                                                  90       83          89                                          II (30° C., 80% RH)                                                                 85       78          85                                          III (15° C., 30% RH)                                                                89       84          89                                          E.sub.1/10  (erg/cm.sup.2)                                                    I (20° C., 65% RH)                                                                  23       33          26                                          II (30° C., 80% RH)                                                                 21       22          23                                          III (15° C., 30% RH)                                                                26       35          28                                          Image Forming*.sup.2)                                                         Performance                                                                   I (20° C., 65% RH)                                                                  Good     Good        Good                                        II (30° C., 80% RH)                                                                 Good     Unevenness  Unevenness                                                        in half tone                                                                              in half tone                                                      area, slight                                                                              area                                                              background fog                                          III (15° C., 30% RH)                                                                Good     White spots in                                                                            White spots                                                       image portion,                                                                            in image                                                          white spots in                                                                            portion                                                           half tone area                                          ______________________________________                                    

The evaluation of each item shown in Table VI-1 was conducted in thefollowing manner.

*1) Electrostatic Characteristics

The light-sensitive material was charged with a corona discharge to avoltage of -6 kV for 20 seconds in a dark room using a paper analyzer("Paper Analyzer SP-428" manufactured by Kawaguchi Denki K.K.). Tenseconds after the corona discharge, the surface potential V₁₀ wasmeasured. The sample was then allowed to stand in the dark for anadditional 90 seconds, and the potential V₁₀₀ was measured. The darkdecay retention rate (DRR; %), i.e., percent retention of potentialafter dark decay for 90 seconds, was calculated from the followingequation:

    DRR(%)=(V.sub.100 /V.sub.10)×100

Separately, the surface of photoconductive layer was charged to -400 Vwith a corona discharge and then exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm), and the time required for decay of the surface potential V₁₀ toone-tenth was measured, and the exposure amount E_(1/10) (erg/cm²) wascalculated therefrom. The measurements were conducted under ambientcondition of 20° C. and 65% RH (I), 30° C. and 80% RH (II) or 15° C. and30% RH (III).

*2) Image Forming Performance

After the light-sensitive material was allowed to stand for one dayunder the ambient condition shown below, the light-sensitive materialwas charged to -6 kV and exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm; output: 2.8 mW) at an exposure amount of 64 erg/cm² (on thesurface of the photoconductive layer) at a pitch of 25 μm and a scanningspeed of 300 m/sec. The thus formed electrostatic latent image wasdeveloped with a liquid developer ("ELP-T" produced by Fuji Photo FilmCo., Ltd.), washed with a rinse solution of isoparaffinic solvent("Isopar G" manufactured by Esso Chemical K.K.) and fixed. Theduplicated image obtained was visually evaluated for fog and imagequality. The ambient condition at the time of image formation was 20° C.and 65% RH (I), 30° C. and 80% RH (II) or 15° C. and 30% RH (III).

As can be seen from the results shown in Table VI-1, the light-sensitivematerial according to the present invention exhibited good electrostaticcharacteristics and provided duplicated image which was clear and freefrom background fog, even when the ambient condition was fluctuated. Onthe contrary, while the light-sensitive materials of ComparativeExamples VI-1 and VI-2 exhibited good image forming performance underthe ambient condition of normal temperature and normal humidity (I), theoccurrence of unevenness of density was observed in the highly accurateimage portions, in particular, half tone areas of continuous gradationunder the ambient condition of high temperature and high humidity (II)regardress of the electrostatic characteristics. Also, a slightbackground fog remained without removing after the rinse treatment.Further, the occurrence of unevenness of small white spots at random inthe image portion was observed under the ambient condition of lowtemperature and low humidity (III).

From all these considerations, it is thus clear that anelectrophotographic light-sensitive material satisfying bothrequirements of electrostatic characteristics and image formingperformance (in particular, for highly accurate image) and beingadvantageously employed particularly in a scanning exposure system usinga semiconductor laser beam can be obtained only when the binder resinaccording to the present invention is used.

EXAMPLE VI-2

A mixture of 5 g (solid basis) of Resin (A-223), 35 g (solid basis) ofResin (B-102), 200 g of photoconductive zinc oxide, 0.020 g of MethineDye (VI-II) shown below, 0.20 g of N-hydroxymaleinimide and 300 g oftoluene was treated in the same manner as described in Example VI-1 toprepare an electrophotographic light-sensitive material. ##STR472##

COMPARATIVE EXAMPLE VI-3

An electrophotographic light-sensitive material was prepared in the samemanner as in Example VI-2, except for using 35 g of Resin (R-VI-3) shownbelow in place of 35 g of Resin (B-102) used in Example VI-2. ##STR473##

COMPARATIVE EXAMPLE VI-4

An electrophotographic light-sensitive material was prepared in the samemanner as in Example VI-2, except for using 35 g of Resin (R-VI-4) shownbelow in place of 35 g of Resin (B-102) used in Example VI-2. ##STR474##

With each of the light-sensitive materials thus-prepared, a filmproperty in terms of surface smoothness, mechanical strength,electrostatic characteristics and image forming performance wereevaluated. Further, printing property was evaluated when it was used asan electrophotographic lithographic printing plate precursor. Theresults obtained are shown in Table VI-2 below.

                                      TABLE VI-2                                  __________________________________________________________________________                             Comparative                                                                            Comparative                                                  Example VI-2                                                                          Example VI-3                                                                           Example VI-4                                __________________________________________________________________________    Smoothness of Photoconductive*.sup.3)                                                          400     350      405                                         Layer (sec/cc)                                                                Mechanical Strength of*.sup.4)                                                                  93      76       87                                         Photoconductive Layer (%)                                                     Electrostatic Characteristics                                                 V.sub.10 (-V)                                                                 I (20° C., 65% RH)                                                                      740     710      730                                         II (30° C., 80% RH)                                                                     725     685      710                                         III (15° C., 30% RH)                                                                    745     700      735                                         D.R.R. (%)                                                                    (90 sec value)                                                                I (20° C., 65% RH)                                                                       91      82       87                                         II (30° C., 80% RH)                                                                      87      78       83                                         III (15° C., 30% RH)                                                                     90      83       86                                         E.sub.1/10  (erg/cm.sup.2)                                                    I (20° C., 65% RH)                                                                       25      39       29                                         II (30° C., 80% RH)                                                                      30      31       31                                         III (15° C., 30% RH)                                                                     31      40       34                                         Image Forming                                                                 Performance                                                                   I (20° C., 65% RH)                                                                      Good    Good     Good                                        II (30° C., 80% RH)                                                                     Good    Unevenness in                                                                          Unevenness in                                                        half tone area,                                                                        half tone area                                                       slight background                                                             stain                                                III (15° C., 30% RH)                                                                    Good    Unevenness in                                                                          White spots in                                                       half tone area,                                                                        image portion                                                        white spots in                                                                image portion                                        Water Retentivity of*.sup.5)                                                                   Good    Severe back-                                                                           Slight background                           Light-Sensitive Material ground stain                                                                           stain                                       Printing Durability*.sup.6)                                                                    10,000 prints                                                                         4,000 prints                                                                           6,000 prints                                __________________________________________________________________________

The evaluation of each item shown in Table VI-2 was conducted in thefollowing manner.

*3) Smoothness of Photoconductive Layer.

The smoothness (sec/cc) of the light-sensitive material was measuredusing a Beck's smoothness test machine (manufactured by Kumagaya RikoK.K.) under an air volume condition of 1 cc.

*4) Mechanical Strength of Photoconductive Layer

The surface of the light-sensitive material was repeatedly (1000 times)rubbed with emery paper (#1000) under a load of 75 g/cm² using a Heidon14 Model surface testing machine (manufactured by Shinto Kagaku K.K.).After dusting, the abrasion loss of the photoconductive layer wasmeasured to obtain film retention (%).

*5) Water Retentivity of Light-Sensitive Material

A light-sensitive material without subjecting to plate making was passedtwice through an etching processor using an aqueous solution obtained bydiluting an oil-desensitizing solution ("ELP-EX" produced by Fuji PhotoFilm Co., Ltd.) to a five-fold volume with distilled water to conduct anoil-desensitizing treatment of the surface of the photoconductive layer.The material thus-treated was mounted on an offset printing machine("611XLA-II Model" manufactured by Hamada Printing Machine ManufacturingCo.) and printing was conducted using distilled water as dampeningwater. The extent of background stain occurred on the 50th print wasvisually evaluated. This tesing method corresponds to evaluation ofwater retentivity after oil-desensitizing treatment of thelight-sensitive material under the forced condition.

*6) Printing Durability

The light-sensitive material was subjected to plate making in the samemanner as described in *2) above to form toner images, and the surfaceof the photoconductive layer was subjected to oil-desensitizationtreatment by passing twice through an etching processor using ELP-EX.The resulting lithographic printing plate was mounted on an offsetprinting machine ("Oliver Model 52", manufactured by Sakurai SeisakushoK.K.), and printing was carried out on paper. The number of printsobtained until background stains in the non-image areas appeared or thequality of the image areas was deteriorated was taken as the printingdurability. The larger the number of the prints, the higher the printingdurability.

As can be seen from the results shown in Table VI-2, the light-sensitivematerial according to the present invention had good surface smoothness,film strength and electrostatic characteristics of the photoconductivelayer. The duplicated image obtained was clear and free from backgroundfog in the non-image area. These results appear to be due to sufficientadsorption of the binder resin onto the photoconductive substance andsufficient covering of the surface of the particles with the binderresin. For the same reason, when it was used as an offset master plateprecursor, oil-desensitization of the offset master plate precursor withan oil-desensitizing solution was sufficient to render the non-imageareas satisfactorily hydrophilic and adhesion of ink was not observed atall as a result of the evaluation of water retentivity under the forcedcondition. On practical printing using the resulting master plate,10,000 prints of clear image without background stains were obtained.

On the contrary, with the light-sensitive materials of ComparativeExamples VI-3 and VI-4, the occurrence of slight background stain innon-image area, unevenness in highly accurate image of continuousgradation and unevenness of white spots in image portion was observedwhen the image formation was conducted under severe conditions. Further,as a result of the test on water retentivity of these light-sensitivematerials to make offset master plates, the adhesion of ink wasobserved. The printing durability thereof was at most 4,000 to 6,000prints.

From these results it is believed that the resin (A) and the resin (B)according to the present invention suitably interacts with zinc oxideparticles to form the condition under which an oil-desensitizingreaction proceeds easily and sufficiently with an oil-desensitizingsolution and that the remarkable improvement in film strength isachieved by the action of the resin (B).

EXAMPLES VI-3 TO VI-22

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example VI-2, except for using each ofResins (A) and Resins (B) shown in Table VI-3 below in place of Resin(A-223) and Resin (B-102) used in Example VI-2, respectively.

                  TABLE VI-3                                                      ______________________________________                                        Example        Resin (A)    Resin (B)                                         ______________________________________                                        VI-3           A-203        B-103                                             VI-4           A-204        B-102                                             VI-5           A-206        B-104                                             VI-6           A-207        B-105                                             VI-7           A-208        B-106                                             VI-8           A-209        B-107                                             VI-9           A-210        B-109                                             VI-10          A-211        B-110                                             VI-11          A-213        B-112                                             VI-12          A-214        B-115                                             VI-13          A-216        B-116                                             VI-14          A-218        B-117                                             VI-15          A-221        B-119                                             VI-16          A-222        B-121                                             VI-17          A-223        B-123                                             VI-18          A-215        B-125                                             VI-19          A-212        B-128                                             VI-20          A-209        B-131                                             VI-21          A-211        B-132                                             VI-22          A-223        B-133                                             ______________________________________                                    

The electrostatic characteristics and image forming performance of eachof the light-sensitive materials were determined in the same manner asdescribed in Example VI-1. Each light-sensitive material exhibited goodelectrostatic characteristics. As a result of the evaluation on imageforming performance of each light-sensitive material, it was found thatclear duplicated images having good reproducibility of fine lines andletters and no occurrence of unevenness in half tone areas without theformation of background fog were obtained.

Further, when these electrophotographic light-sensitive materials wereemployed as offset master plate precursors under the same printingcondition as described in Example VI-2, more than 10,000 good printswere obtained respectively.

It can be seen from the results described above that each of thelight-sensitive materials according to the present invention wassatisfactory in all aspects of the surface smoothness and film strengthof the photoconductive layer, electrostatic characteristics and printingproperty.

EXAMPLES VI-23 TO VI-26

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example VI-1, except for using each of thedye shown in Table VI-4 below in place of Cyanine Dye (VI-I) used inExample VI-1.

                                      TABLE VI-4                                  __________________________________________________________________________    Example                                                                            Dye  Chemical Structure of Dye                                           __________________________________________________________________________    VI-23                                                                              (VI-III)                                                                            ##STR475##                                                         VI-24                                                                              (VI-IV)                                                                             ##STR476##                                                         VI-25                                                                              (VI-V)                                                                              ##STR477##                                                         VI-26                                                                              (VI-VI)                                                                             ##STR478##                                                         __________________________________________________________________________

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided clear duplicated images free frombackground fog even when processed under severe conditions of hightemperature and high humidity (30° C. and 80% RH) and low temperatureand low humidity (15° C. and 30% RH).

EXAMPLES VI-27 AND VI-28

A mixture of 6.5 g of Resin (A-201) (Example VI-27) or Resin (A-211)(Example VI-28), 33.5 g of Resin (B-123), 200 g of zinc oxide, 0.02 g ofuranine, 0.03 g of Methine Dye (VI-VII) shown below, 0.03 g of MethineDye (VI-VIII) shown below, 0.18 g of p-hydroxybenzoic acid and 300 g oftoluene was dispersed by a homogenizer at a rotation of 7×10³ r.p.m. for6 minutes to prepare a coating composition for a light-sensitive layer.The coating composition was coated on paper, which had been subjected toelectrically conductive treatment, by a wire bar at a dry coverage of 25g/m², and dried for 20 seconds at 110° C. Then, the coated material wasallowed to stand in a dark place for 24 hours under the conditions of20° C. and 65% RH to prepare each electrophotographic light-sensitivematerial. ##STR479##

COMPARATIVE EXAMPLE VI-5

An electrophotographic light-sensitive material was prepared in the samemanner as in Example VI-27, except for using 33.5 g of Resin (R-VI-1)described above in place of 33.5 g of Resin (B-123) used in ExampleVI-27.

With each of the light-sensitive materials thus prepared, variouscharacteristics were evaluated in the same manner as in Example VI-2.The results obtained are shown in Table VI-5 below.

                                      TABLE VI-5                                  __________________________________________________________________________                    Example VI-27                                                                         Example VI-28                                                                         Comparative Example VI-5                      __________________________________________________________________________    Binder Resin    (A-201)/(B-123)                                                                       (A-211)/(B-123)                                                                       (A-201)/(R-VI-1)                              Smoothness of Photoconductive                                                                 330     340     335                                           Layer (sec/cc)                                                                Mechanical Strength of                                                                        93      94      86                                            Photoconductive Layer (%)                                                     Electrostatic Characteristics*.sup.7)                                         V.sub.10 (-V)                                                                 I (20° C., 65% RH)                                                                     580     735     565                                           II (30° C., 80% RH)                                                                    565     720     540                                           III (15° C., 30% RH)                                                                   585     740     560                                           D.R.R. (%)                                                                    I (20° C., 65% RH)                                                                     85      95      85                                            II (30° C., 80% RH)                                                                    83      92      80                                            III (15° C., 30% RH)                                                                   86      95      84                                            E.sub.1/10  (lux · sec)                                              I (20° C., 65% RH)                                                                     13.8    8.5     14.0                                          II (30° C., 80% RH)                                                                    12.3    8.3     13.2                                          III (15° C., 30% RH)                                                                   14.5    9.2     15.1                                          Image Forming*.sup.8)                                                         Performance                                                                   I (20° C., 65% RH)                                                                     Good    Very good                                                                             Edge mark of cutting                          II (30° C., 80% RH)                                                                    Good    Very good                                                                             Unevenness in half                                                            tone area                                     III (15° C., 30% RH)                                                                   Good    Very good                                                                             Unevenness of white                                                           spots in image portion,                                                       unevenness in half tone                                                       area                                          Water Retentivity of                                                                          Good    Good    Slight background stain                       Light-Sensitive Material                                                      Printing Durability                                                                           10,000  10,000  Background stain from                                         prints  prints  the start of printing                         __________________________________________________________________________

The characteristics were evaluated in the same manner as in ExampleVI-2, except that some electrostatic characteristics and image formingperformance were evaluated according to the following test methods.

*7) Measurement of Electrostatic Characteristics: E_(1/10)

The surface of the photoconductive layer was charged to -400 V withcorona discharge, and then irradiated by visible light of theilluminance of 2.0 lux. Then, the time required for decay of the surfacepotential (V₁₀) to 1/10 thereof was determined, and the exposure amountE_(1/10) (lux·sec) was calculated therefrom.

*8) Image Forming Performance

The electrophotographic light-sensitive material was allowed to standfor one day under the ambient condition described below, thelight-sensitive material was subjected to plate making by afull-automatic plate making machine (ELP-404V manufactured by Fuji PhotoFilm Co., Ltd.) using ELP-T as a toner. The duplicated image thusobtained was visually evaluated for fog and image quality. The ambientcondition at the time of image formation was 20° C. and 65% RH (I), 30°C. and 80% RH (II) or 15° C. and 30% RH (III). The original used for theduplication was composed of cuttings of other originals pasted upthereon.

From the results, it can be seen that each of the light-sensitivematerials according to the present invention exhibited good mechanicalstrength of the photoconductive layer. On the contrary, with thelight-sensitive material of Comparative Example VI-5 the value ofmechanical strength was lower than them, and the value of E_(1/10) ofelectrostatic characteristics degraded particularly under the ambientcondition of low temperature and low humidity (III), while they weregood under the ambient condition of normal temperature and normalhumidity (I). On the other hand, the electrostatic characteristics ofthe light-sensitive materials according to the present invention weregood. Particularly, those of Example VI-28 using the resin (A') werevery good. The value of E_(1/10) thereof was particularly small.

With respect to image forming performance, the edge mark of cuttingspasted up was observed as background fog in the non-image areas in thelight-sensitive material of Comparative Example VI-5. Also, theoccurrence of unevenness in half tone area of continuous gradation andunevenness of small white spots in image portion was observed on theduplicated image when the ambient conditions at the time of the imageformation were high temperature and high humidity (II) and lowtemperature and low humidity (III). On the contrary, the light-sensitivematerials according to the present invention provided clear images freefrom background fog.

Further, each of these light-sensitive materials was subjected to theoil-desensitizing treatment to prepare an offset printing plate andusing the resulting plate printing was conducted. The plates accordingto the present invention provided 10,000 prints of clear image withoutbackground stains. However, with the plate of Comparative Example VI-5,the above described edge mark of cuttings pasted up was not removed withthe oil-desensitizing treatment and the background stains occurred fromthe start of printing.

It can be seen from the results described above that the light-sensitivematerials according to the present invention was satisfactory in allaspects of the surface smoothness and film strength of thephotoconductive layer, electrostatic characteristics and printingproperty. Further, it can be seen that the electrostatic characteristicsare further improved by the use of the resin (A').

EXAMPLE VI-29

A mixture of 5 g of Resin (A-223), 35 g of Resin (B-122), 200 g of zincoxide, 0.02 g of uranine, 0.04 g of Rose Bengal, 0.03 g of bromophenolblue, 0.40 g of phthalic anhydride and 300 g of toluene was treated inthe same manner as described in Example VI-27 to prepare anelectrophotographic light-sensitive material.

As the result of the evaluation of various characteristics in the samemanner as described in Example VI-27, it can be seen that thelight-sensitive material according to the present invention is excellentin charging properties, dark charge retention rate and photosensitivity,and provides a clear duplicated image free from background fog undersevere conditions of high temperature and high humidity (30° C. and 80%RH) and low temperature and low humidity (15° C. and 30% RH). Further,when the material was employed as an offset master plate precursor,10,000 prints of clear image were obtained.

EXAMPLES VI-30 TO VI-53

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example VI-29, except for using 5 g of eachof Resin (A) and 35 g of each of Resin (B) shown in Table VI-6 below inplace of 5 g of Resin (A-223) and 35 g of Resin (B-122) used in ExampleVI-29, respectively.

                  TABLE VI-6                                                      ______________________________________                                        Example        Resin (A)    Resin (B)                                         ______________________________________                                        VI-30          A-202        B-102                                             VI-31          A-203        B-104                                             VI-32          A-204        B-105                                             VI-33          A-205        B-106                                             VI-34          A-206        B-107                                             VI-35          A-208        B-108                                             VI-36          A-210        B-111                                             VI-37          A-211        B-113                                             VI-38          A-212        B-114                                             VI-39          A-213        B-116                                             VI-40          A-214        B-117                                             VI-41          A-215        B-118                                             VI-42          A-216        B-120                                             VI-43          A-217        B-121                                             VI-44          A-218        B-122                                             VI-45          A-219        B-124                                             VI-46          A-210        B-126                                             VI-47          A-221        B-127                                             VI-48          A-201        B-128                                             VI-49          A-204        B-129                                             VI-50          A-222        B-130                                             VI-51          A-209        B-131                                             VI-52          A-207        B-133                                             VI-53          A-223        B-123                                             ______________________________________                                    

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided a clear duplicated image free frombackground fog and scratches of fine lines even under severe conditionsof high temperature and high humidity (30° C. and 80% RH) and lowtemperature and low humidity (15° C. and 30% RH). Further, when thesematerials were employed as offset master plate precursors, 10,000 printsof a clear image free from background stains were obtained respectively.

EXAMPLE VII-1

A mixture of 6 g (solid basis) of Resin (A-7), 34 g (solid basis) ofResin (B-201), 200 g of photoconductive zinc oxide, 0.018 g of CyanineDye (VII-I) having the following structure, 0.15 g of phthalic anhydrideand 300 g of toluene was dispersed by a homogenizer (manufactured byNippon Seiki K.K.) at a rotation of 6×10³ r.p.m. for 10 minutes toprepare a coating composition for a light-sensitive layer. The coatingcomposition was coated on paper, which had been subjected toelectrically conductive treatment, by a wire bar at a dry coverage of 25g/m², followed by drying at 110° C. for 10 seconds. The coated materialwas then allowed to stand in a dark place at 20° C. and 65% RH for 24hours to prepare an electrophotographic light-sensitive material.##STR480##

COMPARATIVE EXAMPLE VII-1

An electrophotographic light-sensitive material was prepared in the samemanner as in Example VII-1, except for using 34 g of Resin (R-VII-1)having the following structure in place of 34 g of Resin (B-201) used inExample VII-1. ##STR481##

COMPARATIVE EXAMPLE VII-2

An electrophotographic light-sensitive material was prepared in the samemanner as in Example VII-1, except for using 34 g of Resin (R-VII-2)having the following structure in place of 34 g of Resin (B-201) used inExample VII-1. ##STR482##

COMPARATIVE EXAMPLE VII-3

An electrophotographic light-sensitive material was prepared in the samemanner as in Example VII-1, except for using 34 g of Resin (R-VII-3)having the following structure in place of 34 g of Resin (B-201) used inExample VII-1. ##STR483##

With each of the light-sensitive materials thus prepared, electrostaticcharacteristics and image forming performance were evaluated. Theresults obtained are shown in Table VII-1 below.

                                      TABLE VII-1                                 __________________________________________________________________________                            Comparative                                                                           Comparative                                                                           Comparative                                           Example VII-1                                                                         Example VII-1                                                                         Example VII-2                                                                         Example VII-3                         __________________________________________________________________________    Electrostatic Characteristics*.sup.1)                                         V.sub.10 (-V)                                                                 I (20° C., 65% RH)                                                                     810     795     815     805                                   II (30° C., 80% RH)                                                                    800     780     805     790                                   D.R.R. (90 sec value) (%)                                                     I (20° C., 65% RH)                                                                     85      85      85      86                                    II (30° C., 80% RH)                                                                    81      78      81      80                                    E.sub.1/10                                                                    (erg/cm.sup.2)                                                                I (20° C., 65% RH)                                                                     21      23      23      23                                    II (30° C., 80% RH)                                                                    24      26      25      26                                    E.sub.1/100                                                                   (erg/cm.sup.2)                                                                I (20° C., 65% RH)                                                                     34      38      36      40                                    II (30° C., 80% RH)                                                                    40      58      52      61                                    Image Forming Performance*.sup.2)                                             I (20° C., 65% RH)                                                                     Very good                                                                             Scratches of                                                                          Scratches of                                                                          Scratches of                                                  fine lines and                                                                        fine lines and                                                                        fine lines and                                                letters,                                                                              letters,                                                                              letters,                                                      unevenness in                                                                         unevenness in                                                                         unevenness in                                                 half tone area                                                                        half tone area                                                                        half tone area                        II (30° C., 80% RH)                                                                    Very good                                                                             Scratches of                                                                          Scratches of                                                                          Scratches of                                                  fine lines and                                                                        fine lines and                                                                        fine lines and                                                letters,                                                                              letters,                                                                              letters,                                                      unevenness in                                                                         unevenness in                                                                         unevenness in                                                 half tone area                                                                        half tone area                                                                        half tone area                        __________________________________________________________________________

The evaluation of each item shown in Table VII-1 was conducted in thefollowing manner.

*1) Electrostatic Characteristics

The light-sensitive material was charged with a corona discharge to avoltage of -6 kV for 20 seconds in a dark room using a paper analyzer("Paper Analyzer SP-428" manufactured by Kawaguchi Denki K.K.). Tenseconds after the corona discharge, the surface potential V₁₀ wasmeasured. The sample was then allowed to stand in the dark for anadditional 90 seconds, and the potential V₁₀₀ was measured. The darkcharge retention rate (DRR; %), i.e., percent retention of potentialafter dark decay for 90 seconds, was calculated from the followingequation:

    DRR(%)=(V.sub.100 /V.sub.10)×100

Separately, the surface of photoconductive layer was charged to -400 Vwith a corona discharge and then exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm), and the time required for decay of the surface potential V₁₀ toone-tenth was measured, and the exposure amount E_(1/10) (erg/cm²) wascalculated therefrom. Further, in the same manner as described above thetime required for decay of the surface potential V₁₀ to one-hundredthwas measured, and the exposure amount E_(1/100) (erg/cm²) was calculatedtherefrom. The measurements were conducted under ambient condition of20° C. and 65% RH (I) or 30° C. and 80% RH (II).

*2) Image Forming Performance

After the light-sensitive material was allowed to stand for one dayunder the ambient condition shown below, the light-sensitive materialwas charged to -6 kV and exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm; output: 2.8 mW) at an exposure amount of 64 erg/cm² (on thesurface of the photoconductive layer) at a pitch of 25 μm and a scanningspeed of 300 m/sec. The thus formed electrostatic latent image wasdeveloped with a liquid developer ("ELP-T" produced by Fuji Photo FilmCo., Ltd.), washed with a rinse solution of isoparaffinic solvent("Isopar G" manufactured by Esso Chemical K.K.) and fixed. Theduplicated image obtained was visually evaluated for fog and imagequality. The ambient condition at the time of image formation was 20° C.and 65% RH (I) or 30° C. and 80% RH (II).

As can be seen from the results shown in Table VII-1, thelight-sensitive material according to the present invention had goodelectrostatic characteristics. The duplicated image obtained thereon wasclear and free from background fog. On the contrary, with thelight-sensitive materials of Comparative Examples VII-1, VII-2 and VII-3the decrease in photosensitivity (E_(1/10) and E_(1/100)) occurred, andin the duplicated images the scratches of fine lines and letters wereobserved and a slight background fog remained without removing after therinse treatment. Further, the occurrence of unevenness in half toneareas of continuous gradation of the original was observed regardless ofthe electrostatic characteristics.

The value of E_(1/100) is largely different between the light-sensitivematerial of the present invention and those of the comparative examples.The value of E_(1/100) indicates an electrical potential remaining inthe non-image areas after exposure at the practice of image formation.The smaller the value, the less the background fog in the non-imageareas. More specifically, it is required that the remaining potential isdecreased to -10 V or less. Therefore, an amount of exposure necessaryto make the remaining potential below -10 V is an important factor. Inthe scanning exposure system using a semiconductor laser beam, it isquite important to make the remaining potential below -10 V by a smallexposure amount in view of a design for an optical system of aduplicator (such as cost of the device, and accuracy of the opticalsystem).

From all these considerations, it is thus clear that anelectrophotographic light-sensitive material satisfying bothrequirements of electrostatic characteristics and image formingperformance and being advantageously employed particularly in a scanningexposure system using a semiconductor laser beam can be obtained onlywhen the binder resin according to the present invention is used.

EXAMPLE VII-2

A mixture of 5 g (solid basis) of Resin (A-7), 35 g (solid basis) ofResin (B-202), 200 g of photoconductive zinc oxide, 0.020 g of MethineDye (VII-II) having the following structure, 0.20 g ofN-hydroxymaleinimide and 300 g of toluene was treated in the same manneras described in Example VII-1 to prepare an electrophotographiclight-sensitive material. ##STR484##

With the light-sensitive material thus-prepared, a film property interms of surface smoothness, electrostatic characteristics and imageforming performance were evaluated. Further, printing property wasevaluated when it was used as an electrophotographic lithographicprinting plate precursor. The results obtained are shown in Table VII-2below.

                  TABLE VII-2                                                     ______________________________________                                                              Example VII-2                                           ______________________________________                                        Smoothness of Photoconductive Layer*.sup.3)                                                           380                                                   (sec/cc)                                                                      Electrostatic Characteristics                                                 V.sub.10 (-V)                                                                 I (20° C., 65% RH)                                                                             780                                                   II (30° C., 80% RH)                                                                            765                                                   D.R.R.                                                                        (90 sec value) (%)                                                            I (20° C., 65% RH)                                                                             86                                                    II (30° C., 80% RH)                                                                            82                                                    E.sub.1/10  (erg/cm.sup.2)                                                    I (20° C., 65% RH)                                                                             23                                                    II (30° C., 80% RH)                                                                            26                                                    E.sub.1/100  (erg/cm.sup.2)                                                   I (20° C., 65% RH)                                                                             36                                                    II (30° C., 80% RH)                                                                            43                                                    Image Forming Performance                                                     I (20° C., 65% RH)                                                                             Very good                                             II (30° C., 80% RH)                                                                            Very good                                             Contact Angle with Water*.sup.4) (°)                                                           10 or less                                            Printing Durability*.sup.5)                                                                           10,000 prints                                         ______________________________________                                    

The evaluation of each item shown in Table VII-2 was conducted in thefollowing manner.

*3) Smoothness of Photoconductive Layer

The smoothness (sec/cc) of the light-sensitive material was measuredusing a Beck's smoothness test machine (manufactured by Kumagaya RikoK.K.) under an air volume condition of 1 cc.

*4) Contact Angle with Water

The light-sensitive material was passed once through an etchingprocessor using a solution prepared by diluting an oil-desensitizingsolution ("ELP-EX" produced by Fuji Photo Film Co., Ltd.) to a two-foldvolume with distilled water to conduct oil-desensitization treatment onthe surface of the photoconductive layer. On the thus oil-desensitizedsurface was placed a drop of 2 μl of distilled water, and the contactangle formed between the surface and water was measured using agoniometer.

*5) Printing Durability

The light-sensitive material was subjected to plate making in the samemanner as described in *2) above to form toner images, and the surfaceof the photoconductive layer was subjected to oil-desensitizationtreatment under the same condition as in *4) above. The resultinglithographic printing plate was mounted on an offset printing machine("Oliver Model 52", manufactured by Sakurai Seisakusho K.K.), andprinting was carried out on paper. The number of prints obtained untilbackground stains in the non-image areas appeared or the quality of theimage areas was deteriorated was taken as the printing durability. Thelarger the number of the prints, the higher the printing durability.

As can be seen from the results shown in Table VII-2, thelight-sensitive material according to the present invention had goodsurface smoothness and mechanical strength of the photoconductive layerand electrostatic characteristics. The duplicated image obtained wasclear and free from background fog. These results appear to be due tosufficient adsorption of the binder resin onto the photoconductivesubstance and sufficient covering of the surface of the particles withthe binder resin. For the same reason, when it was used as an offsetmaster plate precursor, oil-desensitization of the offset master plateprecursor with an oil-desensitizing solution was sufficient to renderthe non-image areas satisfactorily hydrophilic, as shown by a smallcontact angle of 10° or less with water. On practical printing using theresulting master plate, 10,000 prints of clear image without backgroundstains were obtained.

From these results it is believed that the resin (A) and the resin (B)according to the present invention suitably interacts with zinc oxideparticles to form the condition under which an oil-desensitizingreaction proceeds easily and sufficiently with an oil-desensitizingsolution and that the remarkable improvement in film strength isachieved by the action of the resin (B).

EXAMPLES VII-3 TO VII-24

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example VII-2, except for using each ofResins (A) and Resins (B) shown in Table VII-3 below in place of Resin(A-7) and Resin (B-202) used in Example VII-2, respectively.

                  TABLE VII-3                                                     ______________________________________                                        Example        Resin (A)    Resin (B)                                         ______________________________________                                        VII-3          A-2          B-232                                             VII-4          A-3          B-204                                             VII-5          A-4          B-205                                             VII-6          A-5          B-206                                             VII-7          A-6          B-207                                             VII-8          A-7          B-208                                             VII-9          A-8          B-209                                             VII-10         A-9          B-210                                             VII-11         A-11         B-211                                             VII-12         A-12         B-212                                             VII-13         A-13         B-213                                             VII-14         A-14         B-214                                             VII-15         A-15         B-215                                             VII-16         A-16         B-216                                             VII-17         A-17         B-217                                             VII-18         A-18         B-218                                             VII-19         A-19         B-219                                             VII-20         A-21         B-220                                             VII-21         A-23         B-221                                             VII-22         A-25         B-223                                             VII-23         A-27         B-225                                             VII-24         A-29         B-229                                             ______________________________________                                    

The electrostatic characteristics of the resulting light-sensitivematerials were evaluated in the same manner as described in ExampleVII-2.

The light-sensitive materials according to the present invention wereexcellent in charging properties, dark charge retention rate andphotosensitivity. Also, as a result of the evaluation on image formingperformance of each light-sensitive material, it was found that clearduplicated images having good reproducibility of fine lines and lettersand no occurrence of unevenness in half tone areas without the formationof background fog were obtained.

Further, when these electrophotographic light-sensitive materials wereemployed as offset master plate precursors under the same printingcondition as described in Example VII-2, more than 10,000 good printswere obtained respectively.

EXAMPLES VII-25 TO VII-28

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example VII-1, except for using each of thedyes shown in Table VII-4 below in place of Cyanine Dye (VII-I) used inExample VII-1.

                                      TABLE VII-4                                 __________________________________________________________________________    Example                                                                            Dye  Chemical Structure of Dye                                           __________________________________________________________________________    VII-25                                                                             (VII-III)                                                                           ##STR485##                                                         VII-26                                                                             (VII-IV)                                                                            ##STR486##                                                         VII-27                                                                             (VII-V)                                                                             ##STR487##                                                         VII-28                                                                             (VII-VI)                                                                            ##STR488##                                                         __________________________________________________________________________

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided clear duplicated images free frombackground fog even when processed under severe condition of hightemperature and high humidity (30° C. and 80% RH).

EXAMPLES VII-29 AND VII-30

A mixture of 6 g of Resin (A-1) (Example VII-29) or Resin (A-8) (ExampleVII-30), 34 g of Resin (B-232), 200 g of photoconductive zinc oxide,0.02 g of uranine, 0.03 g of Methine Dye (VII-VII) having the followingstructure, 0.03 g of Methine Dye (VII-VIII) having the followingstructure, 0.18 g of p-hydroxybenzoic acid and 300 g of toluene wasdispersed by a homogenizer at a rotation of 7×10³ r.p.m. for 8 minutesto prepare a coating composition for a light-sensitive layer. Thecoating composition was coated on paper, which had been subjected toelectrically conductive treatment, by a wire bar at a dry coverage of 22g/m², and dried for 20 seconds at 110° C. Then, the coated material wasallowed to stand in a dark place for 24 hours under the conditions of20° C. and 65% RH to prepare each electrophotographic light-sensitivematerial. ##STR489##

COMPARATIVE EXAMPLE VII-4

An electrophotographic light-sensitive material was prepared in the samemanner as in Example VII-29, except for using 34 g of Resin (R-VII-4)having the following structure in place of 34 g of Resin (B-232) used inExample VII-29. ##STR490##

With each of the light-sensitive materials thus prepared, variouscharacteristics were evaluated in the same manner as in Example VII-2.The results obtained are shown in Table VII-5 below.

                                      TABLE VII-5                                 __________________________________________________________________________                    Example VII-29                                                                        Example VII-30                                                                        Comparative Example VII-4                     __________________________________________________________________________    Binder Resin    (A-1)/(B-232)                                                                         (A-8)/(B-232)                                                                         (A-1)/(R-VII-4)                               Smoothness of Photoconductive                                                                 385     400     380                                           Layer (sec/cc)                                                                Electrostatic Characteristics*.sup.6)                                         V.sub.10 (-V)                                                                 I (20° C., 65% RH)                                                                     620     805     595                                           II (30° C., 80% RH)                                                                    605     795     575                                           D.R.R. (%)                                                                    I (20° C., 65% RH)                                                                     90      96      87                                            II (30° C., 80% RH)                                                                    86      93      81                                            E.sub.1/10  (lux · sec)                                              I (20° C., 65% RH)                                                                     10.3    8.5     12.5                                          II (30° C., 80% RH)                                                                    11.0    9.6     13.8                                          E.sub.1/100  (lux · sec)                                             I (20° C., 65% RH)                                                                     16      14      23                                            II (30° C., 80% RH)                                                                    19      17      27                                            Image Forming*.sup.7)                                                         Performance                                                                   I (20° C., 65% RH)                                                                     Good    Very good                                                                             Edge mark of cutting                          II (30° C., 80% RH)                                                                    Good    Very good                                                                             Edge mark of cutting,                                                         unevenness in                                                                 half tone area                                Contact Angle with Water (°)                                                           10 or less                                                                            10 or less                                                                            10 or less                                    Printing Durability                                                                           10,000  10,000  Background stain                                              prints  prints  due to edge mark of                                                           cutting from the                                                              start of printing                             __________________________________________________________________________

The characteristics were evaluated in the same manner as in ExampleVII-2, except that some electrostatic characteristics and image formingperformance were evaluated according to the following test methods.

*6) Measurement of Electrostatic Characteristics: E_(1/10) and E_(1/10)0

The surface of the photoconductive layer was charged to -400 V withcorona discharge, and then irradiated by visible light of theilluminance of 2.0 lux on the surface of the photoconductive layer.Then, the time required for decay of the surface potential (V₁₀) to 1/10or 1/100 thereof was determined, and the exposure amount E_(1/10) orE_(1/100) (lux·sec) was calculated therefrom.

*7) Image Forming Performance

The electrophotographic light-sensitive material was allowed to standfor one day under the ambient condition described below, thelight-sensitive material was subjected to plate making by afull-automatic plate making machine (ELP-404V manufactured by Fuji PhotoFilm Co., Ltd.) using ELP-T as a toner. The duplicated image thusobtained was visually evaluated for fog and image quality. The ambientcondition at the time of image formation was 20° C. and 65% RH (I) or30° C. and 80% RH (II). The original used for the duplication wascomposed of cuttings of other originals pasted up thereon.

From the results shown above, it can be seen that each light-sensitivematerial exhibited almost same properties with respect to the surfacesmoothness of the photoconductive layer. However, on the electrostaticcharacteristics, the light-sensitive material of Comparative ExampleVII-4 had the particularly large value of photosensitivity E_(1/100),and this tendency increased under the high temperature and high humiditycondition. On the contrary, the electrostatic characteristics of thelight-sensitive material according to the present invention were good.Further, those of Example VII-30 using the resin (A') were very good.The value of E_(1/100) thereof was particularly small.

With respect to image forming performance, the occurrence of the edgemark of cuttings pasted up was observed as background fog in thenon-image areas in the light-sensitive material of Comparative ExampleVII-4. On the contrary, the light-sensitive materials according to thepresent invention provided clear duplicated images free from backgroundfog.

Further, each of these light-sensitive materials was subjected to theoil-desensitizing treatment to prepare an offset printing plate andusing the resulting plate printing was conducted. The plates accordingto the present invention provided 10,000 prints of clear image withoutbackground stains. However, with the plate of Comparative Example VII-4,the above described edge mark of cuttings pasted up was not removed withthe oil-desensitizing treatment and the background stains occurred fromthe start of printing.

It can be seen from the results described above that each of thelight-sensitive materials according to the present invention wassatisfactory in all aspects of the surface smoothness and film strengthof the photoconductive layer, electrostatic characteristics, andprinting property. Also, it can be seen that the electrostaticcharacteristics are further improved by the use of the resin (A').

EXAMPLE VII-31

A mixture of 5 g of Resin (A-29), 35 g of Resin (B-230), 200 g ofphotoconductive zinc oxide, 0.02 g of uranine, 0.04 g of Rose Bengal,0.03 g of bromophenol blue, 0.40 g of phthalic anhydride and 300 g oftoluene was treated in the same manner as described in Example VII-29 toprepare an electrophotographic light-sensitive material.

As the result of the evaluation of various characteristics in the samemanner as described in Example VII-29, it can be seen that thelight-sensitive material according to the present invention wasexcellent in charging properties, dark charge retention rate andphotosensitivity, and provided a clear duplicated image free frombackground fog under severe conditions of high temperature and highhumidity (30° C. and 80% RH). Further, when the material was employed asan offset master plate precursor, 10,000 prints of clear image wereobtained.

EXAMPLES VII-32 TO VII-49

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example VII-31, except for using 6 g of eachof Resin (A) and 34 g of each of Resin (B) shown in Table VII-6 below inplace of 5 g of Resin (A-29) and 35 g of Resin (B-230) used in ExampleVII-31, respectively.

                  TABLE VII-6                                                     ______________________________________                                        Example        Resin (A)    Resin (B)                                         ______________________________________                                        VII-32         A-2          B-203                                             VII-33         A-4          B-204                                             VII-34         A-5          B-207                                             VII-35         A-9          B-209                                             VII-36         A-11         B-213                                             VII-37         A-12         B-216                                             VII-38         A-13         B-217                                             VII-39         A-20         B-221                                             VII-40         A-21         B-224                                             VII-41         A-26         B-226                                             VII-42         A-27         B-231                                             VII-43         A-28         B-233                                             VII-44         A-101        B-201                                             VII-45         A-110        B-202                                             VII-46         A-130        B-208                                             VII-47         A-202        B-220                                             VII-48         A-216        B-228                                             VII-49         A-223        B-230                                             ______________________________________                                    

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided a clear duplicated image free from theoccurrence of background fog and scratches of fine lines even undersevere condition of high temperature and high humidity (30° C. and 80%RH). Further, when these materials were employed as offset master plateprecursors, 10,000 prints of a clear image free from background stainswere obtained respectively.

POSSIBILITY OF UTILIZATION IN INDUSTRY

In accordance with the present invention, an electrophotographiclight-sensitive material which exhibits excellent electrostaticcharacteristics (particularly, under severe conditions) and mechanicalstrength and provides clear images of good quality can be obtained. Theelectrophotographic light-sensitive material according to the presentinvention is particularly useful in the scanning exposure system using asemiconductor laser beam. The electrostatic characteristics are furtherimproved by using the resin according to the present invention whichcontains a reapeating unit having the specific methacrylate component.

What is claimed is:
 1. An electrophotographic light-sensitive material having a photoconductive layer containing at least an inorganic photoconductive substance, a spectral sensitizing dye and a binder resin, wherein the binder resin comprises at least one resin (A) and at least one resin (B):resin (A): a resin having a weight average molecular weight of from 1×10³ to 2×10⁴ and containing not less than 30% by weight of a polymer component corresponding to a repeating unit represented by the general formula (I) described below and from 0.5 to 15% by weight of a polymer component containing at least one polar group selected from the group consisting of --PO₃ H₂, --SO₃ H, --COOH, ##STR491## (wherein R¹ is selected from the group consisting of a hydrocarbon group and --OR² (wherein R² represents a hydrocarbon group)) and a cyclic acid anhydride-containing group; ##STR492## (wherein a¹ and a² each is selected from the group consisting of a hydrogen atom, a halogen atom, a cyano group, a hydrocarbon group, --COOR⁴ and --COOR⁴ bonded via a hydrocarbon group (wherein R⁴ represents a hydrocarbon group); and R³ represents a hydrocarbon group;resin (B): a starlike polymer having a weight average molecular weight of from 3×10⁴ to 1×10⁶ and comprising an organic molecule having bonded thereto at least three polymer chains each containing a polymer component containing at least one polar group selected from the group consisting of the specified polar groups as described in the resin (A) above and a polymer component corresponding to a repeating unit represented by the general formula (I) as described in the resin (A) above, wherein the polymer contains the polymer component containing a polar group in an amount of from 0.01 to 10% by weight and the polymer component corresponding to the general formula (I) in an amount not less than 30% by weight.
 2. An electrophotographic light-sensitive material as claimed in claim 1, wherein the resin (A) contains, as the polymer component represented by the general formula (I), at least one methacrylate component having an aryl group selected from the group consisting of the following general formulae (Ia) and (Ib): n ##STR493## wherein T₁ and T₂ each is selected from the group consisting of a hydrogen atom, a halogen atom, a hydrocarbon group having from 1 to 10 carbon atoms, --COR_(a) and --COOR_(a) wherein R_(a) represents a hydrocarbon group having from 1 to 10 carbon atoms; and L₁ and L₂ each is selected from the group consisting of a mere bond and a linking group containing from 1 to 4 linking atoms, which connects --COO-- and the benzene ring.
 3. An electrophotographic light-sensitive material as claimed in claim 1, wherein the total amount of the specific polar group-containing polymer component contained in the resin (B) is from 10 to 50% by weight based on the total amount of the specific polar group-containing polymer component present in the resin (A).
 4. An electrophotographic light-sensitive material as claimed in claim 1, wherein the polar group-containing polymer component is present in the polymer chain of the resin (A).
 5. An electrophotographic light-sensitive material as claimed in claim 1, wherein the polar group-containing polymer component is present at one terminal of the polymer chain of the resin (A).
 6. An electrophotographic light-sensitive material as claimed in claim 1, wherein the polar group-containing polymer component is present both in the polymer chain and at the terminal of the polymer chain of the resin (A).
 7. An electrophotographic light-sensitive material as claimed in claim 4, wherein the polar group-containing polymer component is present at random in the polymer chain of the resin (A).
 8. An electrophotographic light-sensitive material as claimed in claim 4, wherein the polar group-containing polymer component is present in the form of a block in the polymer chain of the resin (A).
 9. An electrophotographic light-sensitive material as claimed in claim 1, wherein the polymer chain in the resin (B) is an AB block polymer chain composed of an A block comprising a polymer component containing the polar group and a B block comprising a polymer component corresponding to the general formula (I).
 10. An electrophotographic light-sensitive material as claimed in claim 1, wherein the polymer chain in the resin (B) comprises a polymer component corresponding to the general formula (I), is bonded to the organic molecule at one terminal thereof and has a polymer component containing the specified polar group at the other terminal thereof.
 11. An electrophotographic light-sensitive material as claimed in claim 9, wherein the polymer chain in the resin (B) is an AB block copolymer chain in which a polymer component containing the specified polar group is bonded at one terminal of the A block polymer chain and the B block polymer chain is bonded at the other terminal of the A block polymer chain. 